"This world lost a shining light."

Saugus High School student Haley Stuart hugs family members at a memorial to the two students killed a day earlier. Photo: Kent Nishimura/Los Angeles Times. Click to enlarge.

He was the oldest of four brothers, a football player with a goofy grin. "A little guy with a big heart," a friend said.

She was a cheerleader who loved fashion and brought out the best in other people. A friend remembered: "You would just smile looking at her."

Dominic Blackwell, 14, and Gracie Anne Muehlberger, 15, were killed this week when a gunman opened fire at their high school in Santa Clarita. The two are now united by a tragedy that has become all too common on school campuses nationwide.

On Thursday morning, a 16-year-old student pulled a pistol from his backpack and began firing in the quad at Saugus High School. He wounded five students, then turned the gun on himself, officials said.

The shooter was pronounced dead Friday. The other three teenagers who were shot are expected to recover, doctors say.

By late Friday afternoon, the horror and shock of another school gave way to mourning in Santa Clarita.

Dozens gathered at a makeshift memorial at the city's Central Park, just a short walk from the high school. Candles and teddy bears piled up on the grass around a pole from which an American flag flew at half-staff.

Sebastian Martinez, 12, placed a football on the grass in honor of Dominic, whom he played football with in a youth program.

The boy arrived at the park just before nightfall with his father, Xavier Martinez, who had grown to know Dominic's family through their sons' friendship. Martinez said he spent most of Thursday with Dominic's family.

"He was always smiling and laughing," the older Martinez said of Dominic. "It's so unfair."

Dominic was remembered by friends and family as a jokester with a huge grin. His Instagram page includes the name "comedian," a clear nod to his budding comedic persona.

Anthony Martinez, a student at Canyon High School, called Dominic not just his teammate, but his brother.

Sisters Isabella Esser, 16, and Sophoia Esser, 12, embrace at a memorial to the victims at Santa Clarita's Central Park, a short walk from Saugus High School. Photo: Kent Nishimura/Los Angeles Times. Click to enlarge.

"He was always smiling, making people laugh, always positive, he was the sweetest kid ever," Anthony wrote on Twitter. "We need more people like you."

On a GoFundMe page, Dominic's family remembered his "goofy laugh, cheesy smile, a huge, caring heart."

"This world lost a bright, shining light," the page reads. "He was taken from his family and friends in the most senseless of ways. His three brothers will miss their big brother greatly."

On Thursday, Saugus High, home to 2,500 students, joined a long list of schools that have doubled as sites of mass shootings. Police said the shooting started and ended in just 16 seconds.

One victim, a 14-year-old boy, was treated at a hospital and released Thursday afternoon.

Two girls, 15 and 14, remain at Providence Holy Cross Medical Center in Mission Hills and are now in the same room, surrounded by their families.

The 15-year-old was shot below the navel, authorities said. The bullet lodged in her hip and was removed by doctors.

The 14-year-old had wounds to her left shoulder and lower abdomen, doctors said Friday.

Both girls are expected to be released within a few days.

Investigators said the attack was planned but they do not believe specific students were targeted.

Gracie had celebrated a birthday Oct. 10. She was described by classmates as sweet and fun, someone who had a momentous impact in her short life.

Alexa Olsen, a freshman at Saugus High who was in a dance class with Gracie, remembered her as a goofy, fun girl who cheered her on.

When the girls made eye contact in the middle of practice as they danced to jazz, Gracie would make funny faces and the two would burst out laughing, Alexa said. When they made a mistake, the two would laugh together and keep on dancing.

"She was so nice and kind to everyone," said Alexa, 14. "You would just smile looking at her."

Chloe White, 17, who helped coach the girls cheerleading team, said Gracie had a bright personality and always looked as if she enjoyed being onstage. She was quick to throw out encouragement to her teammates as they got ready to perform.

"She was always telling people they could do it," Chloe said. "'You got this, guys, you're going to be great.'"

Gracie's parents said in a GoFundMe campaign that they are searching for a way to memorialize their daughter. The account raised more than $9,000 in its first hour.

"It is with the most unexplainable brokenness that we share our Gracie went to be with Jesus on Thursday morning," the page reads. "Our vivacious, funny, loyal, light of our lives, Cinderella, the daughter we always dreamed to have, fiercely strong and lover of all things fashionable — was our best friend. She is going to be missed more than words will ever be able to express."

The Muehlbergers concluded the post with a message to Gracie: "We will love you always Sweetpea."

Times staff writer Hannah Fry contributed to this report.

Gracie Anne Muehlberger, 15, in a family photo earlier this year. Courtesy of Muehlberger family.

Los Angeles County coroner's officials have identified the two teenagers shot and killed Thursday in a horrific 16-second attack in which police say a 16-year-old student opened fire on his classmates.

Gracie Anne Muehlberger, 15, died at Henry Mayo Newhall Hospital in Valencia at 9:23 a.m., authorities said Friday. She had celebrated a birthday Oct. 10.

Dominic Blackwell, 14, died Thursday.

Law enforcement officials have placed a security hold on the girl's case, meaning no information about her death will be released until the hold is lifted.

On Thursday morning, not long before the start of the second period of the school day, a 16-year-old boy pulled a .45-caliber pistol from his backpack and began shooting, sheriff's officials said. He wounded five other students, then turned the gun on himself, Los Angeles County Sheriff Alex Villanueva said.

It was all over too quickly for anyone to intervene, although law enforcement was on the scene within moments.

Gracie's parents said in a GoFundMe campaign they are searching for a way to memorialize their daughter. The account raised more than $9,000 in its first hour.

"It is with the most unexplainable brokenness that we share our Gracie went to be with Jesus on Thursday morning," the page reads. "Our vivacious, funny, loyal, light of our lives, Cinderella, the daughter we always dreamed to have, fiercely strong and lover of all things fashionable — was our best friend. She is going to be missed more than words will ever be able to express."

The Muehlbergers concluded the post with a message to Gracie: "We will love you always Sweetpea."

Dominic Blackwell, 14.

Gracie was described by classmates as sweet and fun, someone who made a momentous impact in her short life. Alexa Olsen, a freshman at Saugus High School who was in a dance class with Gracie, said she remembered her as a goofy, fun girl who cheered her on.

When the girls made eye contact in the middle of practice as they danced to jazz, Gracie would make funny faces and the two would burst out laughing, Alexa said. When they made a mistake, the two would laugh together and keep on dancing.

"She was so nice and kind to everyone," said Alexa, 14. "You would just smile looking at her."

Though the girls no longer had dance class together, Gracie would still wave and smile when they passed each other in the hallway, Alexa said.

"She knew everyone and everyone knew her. It's sad she passed away at such a young age and didn't get to experience what other people experience."

In the hours after the attack, friends and family took to social media to express their anguish over the shooting.

"My heart is killing me right now," a person who identified himself as Gracie's brother posted on Twitter. "You are the best sister I could've asked for. I just know you're my guardian angel now. I love you Gracie."

More than 4,500 people — many of them classmates but some strangers — commented on Gracie's sole post on Instagram, which appears to be a silhouetted image of herself.

On Instagram, classmates and friends posted videos of the teen dancing and group selfies filled with funny faces and laughter.

You were the pretty one with the sweetest soul.

I'm really glad I had the chance to meet someone as great as Gracie.

I still don't believe that you are gone, and I don't want to.

A photo on Facebook shows her smiling broadly beside her two brothers. Her knee pops up in one image. In another, she affectionately holds on to her brother's arm.

In what appears to be a Twitter account belonging to Gracie, a post from last fall shares a young girl's desire for new clothes.

Video of Dominic posted to Instagram show a young beaming boy, making faces at the camera amid off-screen laughter. His Instagram page includes the name "comedian," a clear nod to his budding comedic persona.

A separate GoFundMe account launched in support of the Saugus High School community and started by two alums has raised more than $15,000, already surpassing its $10,000 goal. The page states that funds will be donated to memorials, grief counseling and trauma support.

Of the other teens who were shot, two girls. ages 15 and 14, remained hospitalized Friday but are expected to recover, doctors said. The girls are now in the same room at Providence Holy Cross Medical Center in Mission Hills, surrounded by their families.

The 15-year-old was shot below the navel, authorities said. The bullet lodged in her hip and was removed by doctors. The 14-year-old had wounds to her left shoulder and lower abdomen, doctors said Friday. Both girls are expected to be released in the next day or two.

Another student, a 14-year-old boy, was treated and released Thursday afternoon from nearby Henry Mayo Newhall Hospital.

Times staff writer Hannah Fry contributed to this report.

Nathaniel Berhow, 16.

The teenage shooter who opened fire at Saugus High School before shooting himself in the head died Friday of his injuries, as investigators seized unregistered firearms from his home and tried to determine the origin of the handgun used in the deadly attack.

Authorities say Nathaniel Berhow carried out the violence at the Santa Clarita campus on his 16th birthday after being dropped off at school by his mother. School surveillance video reviewed by law enforcement shows him pulling a pistol from his backpack and opening fire in the quad, killing a 15-year-old girl and a 14-year-old boy and wounding three others in an attack that lasted 16 seconds.

At one point during the gunfire, the weapon jammed and the shooter cleared the firearm before he continued firing. He appeared to know how many shots he had fired and left the final round for himself, ending the attack with a gunshot to his head, Los Angeles County Sheriff Alex Villanueva said Thursday.

The teen died of that wound Friday afternoon, with his mother at the hospital with him.

Investigators believe the attack was planned but said they do not think specific students were targeted.

"He seemed very familiar with firing the weapon," Villanueva said. He added that the shooting was not a "spur of the moment act," but officials have not determined a motive.

Federal and state investigators were also trying to determine whether the handgun used by the shooter was assembled from parts purchased separately, law enforcement sources told The Times.

Such so-called ghost guns are unserialized weapons manufactured from parts that can be ordered through the mail or machined parts acquired from underground makers.

Two people visit a makeshift memorial in Santa Clarita's Central Park to victims of Thursday's shooting. Photo: Irfan Khan/Los Angeles Times. Click to enlarge.

The sources said the gun design appeared to be unusual but emphasized that officials don't know its origins at this time.

Investigators found several firearms during a search of the teen's home, some of which were not registered. Villanueva did not specify what types of guns were recovered. The L.A. County Sheriff's Department is working with the federal Bureau of Alcohol, Tobacco, Firearms and Explosives to trace the origins of the .45-caliber handgun that was used in the shooting.

Deputy James Callahan, a school resource officer at Saugus, said he was on his way to campus when the shooter call went out Thursday. When he arrived minutes later, he rushed to help students wounded in the quad along with other off-duty law enforcement officers who were already rendering aid.

"When you're a school resource deputy, you take a lot of pride in keeping your campus secure," he said. "You never think a tragic thing like this is going to happen."

A day after the gunfire, students, parents and law enforcement officers described the tightknit community as being in a state of mourning. Many continued to struggle with the violence that had unfolded.

Xitlali Rodriguez, 16, had been sitting in her first-period digital photo class when she heard the gunshots. The classroom door was wide open, she said, and she was just one building away from the quad where the shooter opened fire.

She said she thought she was going to die. The students did their best to keep a low profile: They closed the door, shut off the lights and hid in the room. Everyone was texting family and friends. She watched as some cried silently while others hugged, trying to comfort one another.

Rodriguez said she talked to the emotional support counselors at school, who told her she was suffering from acute post-traumatic stress disorder.

"I'm thankful to be around family, and I'm happy that I am safe," she said, "but I'm scared to go to school or large public areas now, and no one should have to feel like that."

Coroner's officials on Friday identified the 15-year-old girl who died in the shooting as Gracie Anne Muehlberger and the 14-year-old boy who died as Dominic Blackwell.

Vicky Villarreal and Matthew Arauz visit the memorial at Central Park. Photo: Kent Nishimura/Los Angeles Times. Click to enlarge.

Two teenage girls who were wounded in the shooting remained hospitalized Friday but were expected to recover from their injuries.

One of those girls, 15, arrived Thursday at Providence Holy Cross Medical Center with a gunshot wound below her belly button, doctors say. The bullet, which had lodged in her hip, was removed by surgeons.

The other, 14, arrived at the same hospital with gunshot wounds to her left shoulder and lower abdomen. Both girls are expected to be released in the next day or two, doctors say. The teens are staying in the same room and are surrounded by their families.

"Once we were done with the work-up, they were both sitting up, smiling and talking," Dr. Boris Borazjani said during a morning news conference at the hospital.

A third injured student, a 14-year-old boy, was treated and released Thursday from the hospital. His specific injuries were not revealed.

Kaitlin Holt never expected to experience a school shooting in her first teaching job — or to have to act as a first responder.

But that's what the 26-year-old Saugus High School choir teacher did Thursday morning. Holt's students had been listening to a recording of themselves singing at a jazz festival when several students ran into her classroom. They told her they had heard gunshots.

"It was just fight or flight," Holt said. "I didn't have time to think of anything except of survival for my students."

She locked and barricaded the door, moving her students into an office within the classroom. Once inside, one of the students who had run in told Holt that she thought she had gotten shot.

"Her adrenaline was so high she didn't know she had been shot," Holt said.

The girl, a freshman, had been shot on her right side and on her left shoulder. Months before, during a school staff meeting, Holt had watched a tutorial on how to use a gunshot wound kit. She left her office to get a kit from her classroom and wrapped the wound on the girl's side while putting pressure on the shoulder wound.

Meanwhile, a senior student called the police to let them know about the wounded student. Another senior guarded the door of the office with a fire extinguisher. After about 20 minutes, police came into the classroom and told the students they could leave the room. Though the incident shook Holt, she said it hasn't deterred her from wanting to teach.

"I just don't think this should be part of my job," she said.

Detectives have conducted 40 interviews and still have six to go in their efforts to piece together what led up to Thursday's shooting. They've also searched the shooter's papers and computer hard drives for any clues as to a motive, but so far, none has emerged. The teen didn't leave behind a suicide note or manifesto detailing any plans, Sheriff's Capt. Kent Wegener said Friday.

Friends and neighbors of the shooter were stunned, saying the teen showed no signs of aggression. He ran junior varsity cross-country and helped younger members in his Boy Scout troop. Classmates described him as being very intelligent, an academic achiever who often received the highest marks in his classes.

"He was pretty funny too," Brooke Risley, 16, said. "He had a higher-level type of humor that often I couldn't even get the joke 'cause it was above my head."

However, public records and a high-ranking law enforcement source indicated there were signs of trouble at home.

His family life in Santa Clarita had been upended by his father's sudden death in December 2017, acquaintances said. More recently, a source told The Times that the boy was having problems with his girlfriend, who was his emotional anchor.

The teen's father, Mark Berhow, had been arrested on suspicion of driving under the influence in 2013 and 2015 and pleaded no contest twice. The second time, he was sentenced to 45 days in jail and five years' probation.

According to jail records, he was also booked in 2015 on suspicion of attempted battery of a spouse. Prosecutors declined to file charges in that case, citing insufficient evidence.

Times staff writers Sarah Parvini, James Queally, Soumya Karlamangla and Alejandra Reyes-Velarde contributed to this report.

Santa Clarita residents gather in prayer at Grace Baptist Church on Thursday. Photo: Luis Sinco/Los Angeles Times. Click to enlarge.

Investigators are still trying to determine what led to a deadly attack at Saugus High School on Thursday in which police and witnesses say a 16-year-old student opened fire in the campus quad, killing two classmates and injuring three others before turning the gun on himself.

Detectives have conducted 40 interviews and still have six to go in their efforts to piece together what led up to the shooting in Santa Clarita. It is not clear how the shooter got the weapon, a .45-caliber handgun. However, authorities say that at this point, they do not think the shooter targeted specific students.

Authorities seized several unregistered firearms from the teenager's home , and the Los Angeles County Sheriff's Department is working with the federal Bureau of Alcohol, Tobacco, Firearms and Explosives to trace the origins of the handgun used in the shooting, Sheriff Alex Villanueva said.

"We are chasing all the leads available," Villanueva said. "At this stage, we don't know the motive."

Just before the start of second period on Thursday, authorities and witnesses say, Nathaniel Berhow pulled a .45-caliber pistol from his backpack and began shooting his schoolmates. The attack was launched on his 16th birthday. The boy died of his wounds Friday.

A school surveillance camera recorded the 16 seconds of violence, investigators said. The teenager apparently knew how many shots he had fired and reserved the final round for himself, Villanueva said.

Friends and neighbors were stunned, saying the teenager had not shown signs of aggression. He ran junior varsity cross-country and helped younger members in his Boy Scout troop.

"He would have fun with the team and was a good kid," 11th-grader Aidan Soto said. "The younger Scouts really looked up to him. He was there when they needed him with anything. I'm bewildered and looking for answers."

Brooke Risley, a 16-year-old junior at Saugus High, has known the teen since elementary school. Last year, the two were together in a group for their engineering class and grew to become close friends.

"He was very smart and really good at history," she said.

In AP European history class, she said, he would help her study and would often get the highest test scores in the class. She said the teen often planned Boy Scout trips during their free time in class last year.

"He was pretty funny too," she said. "He had a higher-level type of humor that often I couldn't even get the joke 'cause it was above my head."

When word began to spread, a friend reached out and let her know. In shock, she began texting a mutual friend.

"Please tell me it's not Nathaniel," she said.

"I heard that too," he responded. "I don't want to believe it."

A senior in their class last year reached out to her Friday, asking whether it was the same Nathaniel who was on their group project "because he couldn't believe he would do this," Risley said.

"Everyone who has heard about him being the shooter has said this wasn't typically him," she said. "All those who know him are really wondering what the motive was."

Public records and a high-ranking law enforcement source have indicated signs of trouble at home.

His family life in Santa Clarita was upended by his father's sudden death in December 2017, acquaintances said. More recently, a source told The Times that the boy was having problems with his girlfriend, who was his emotional anchor.

The teen's father, Mark Berhow, was arrested on suspicion of driving under the influence in 2013 and 2015 and pleaded no contest twice. The second time, he was sentenced to 45 days in jail and five years' probation.

According to jail records, he was also booked in 2015 on suspicion of attempted battery of a spouse. The Los Angeles County district attorney's office declined to file charges in that case, citing insufficient evidence.

A judge granted physical custody of the boy to his mother in August 2016, even though both parents still appeared to live in the family's small ranch home on Sycamore Creek Drive.

"He would tell me that he missed his father and that he loved him," said neighbor Jared Axen, 33.

Santa Clarita residents gather in prayer at Grace Baptist Church on Thursday night after the deadly shooting at nearby Saugus High School. Photo: Luis Sinco/Los Angeles Times. Click to enlarge.

The crisis was over, the danger had passed, and Saugus High students were wandering bewildered through a sea of squad cars and news vans, trying to wrap their minds around what had just transpired on the campus quad.

"I never thought this would happen in Santa Clarita." That familiar refrain was all many students could think of to say when a newscaster stuck a microphone in their face.

They'd felt safe in the cosseted security of their close-knit suburban community, the hometown of so many law enforcement officers. Now, they were those kids who'd lived through a campus shooting. They were suddenly swathed in vulnerability.

"It doesn't seem like this is something that should happen here," a sophomore named Adriana told a reporter. She'd heard the gunshots from her home, as she was setting off for campus. Hours later, I could hear the mix of fear and outrage in her voice.

"I'm honestly terrified to go to school. You never really know if something like this could happen again." She didn't feel prepared for this, she said.

But how on earth do you prepare for the prospect that one of your classmates — an ordinary kid, a Boy Scout who played chess, ran cross-country, had a girlfriend, took AP classes — would begin the school day by pulling a gun from his backpack and shooting into a crowd on the quad?

How do you protect yourself from something you can't predict and don't understand?

* * *

That's a question we've been asking ever since the shocking massacre 20 years ago at Colorado's Columbine High School. The murder of a teacher and 12 students by a pair of misfit classmates on a deadly rampage jangled us free from the notion of school as a safe space.

That tragedy is blamed by experts for sparking a wave of school shootings that has taken more than 350 lives, shows no sign of ending and spawned an industry of school-shooter protection programs to prepare for what was once unthinkable.

"Students today should be as familiar with active shooter protocols as they are with fire drills or protocols for earthquakes and other natural disasters," said USC professor Erroll Southers, a former FBI agent and director of the university's Safe Communities Institute.

For the last 20 years, he's been visiting schools across the country, assessing everything from where the classroom windows are to how many kids sit alone in the lunchroom.

In some ways, protecting students has become its own sort of arms race, with schools going to such extremes that school-shooter training might actually traumatize the students it's intended to protect.

"There's a school of thought that you have to enact sensorial training drills — firing blank guns and tackling individuals — to make it a real life experience," said Melissa Reeves, a Winthrop University professor who helped write a national curriculum for school crisis interventions. "But we don't light a fire in the hallway to do fire drills."

In fact, that kind of visceral experience can provoke such an intense emotional response that students wind up more scared than prepared.

Most schools prepare teachers and students as Saugus High did, with routine lockdown drills, often built on a hierarchical mantra of survival options: Run, hide, fight.

Critics worry that's not enough to equip young people; that students will panic and freeze when a real crisis occurs.

But the response of Saugus High students and teachers to Thursday's crisis suggests otherwise. They married instinct with preparation and did their campus and community proud.

I watched their stories unfold in news interviews on a day of relentless television coverage. Their presence of mind astounded me.

Students who could fled the campus at the sound of gunshots and shouted warnings to others. There was panic and confusion, but there was no stampede.

Teachers guided kids away from danger, yanked them into classrooms, shoved them into safe spaces, and calmly issued orders — turn those cellphones off — that teenagers efficiently obeyed.

Behind locked doors, desks became barriers, fire extinguishers were marshaled as weapons, and students armed themselves with scissors, "just in case you have to fight back," one boy told reporters.

And in the eerie quiet of a choir practice room, an injured student who'd stumbled in bloody from the quad assured worried schoolmates that she would be OK — as a teacher dressed her two bullet wounds with supplies from the classroom's gunshot wound kit, lamenting only that she didn't have a second kit.

* * *

The mere idea that classrooms today need gunshot wound kits makes me want to cry.

But that's our new reality in this country. And no neighborhood can expect to be immune.

I could sense the students' soul-searching as they tried to answer the question that virtually every reporter asked: How do you feel?

This was unfamiliar territory for them. They'd grown up in a community considered one of the safest cities for children in America. They went to school with kids they'd known all their lives.

And there they were, walking off campus in a single-file line, many in tears, with their arms above their heads like criminals on TV, being herded away from a crime scene.

They felt scared, confused, grateful, angry, stunned. And all the grown-ups had to offer them in the moment were hugs and refrains of "Thank God you are OK."

I couldn't stop thinking about Adriana casting about for some sign that things could be made OK, longing for the kind of protections that urban schools are trying to get rid of.

"We have open gates," she complained. "We don't check IDs. There's no metal detectors. Maybe we need metal detectors."

But who wants schools to look like penitentiaries?

"You could put all the physical protectors in place ... and still there's no way we can stop everything bad from happening," said Reeves, a former president of the National Assn. of School Psychologists. "The more you make it like a fortress, the more they feel unsafe."

Her advice has nothing to do with searches or equipment:

"We've got to deal with this on the front end with kids, so they're not feeling so hopeless and angry and desperate."

It seems to me we're all feeling a little desperate right now, wishing there was one right answer — just do this and you will be safe.

But that doesn't really exist, inside or outside of school, in our world today.