Two students were killed when a 16-year-old classmate pulled a handgun from his backpack and opened fire Thursday morning at a high school in Santa Clarita.

Police and firefighters responded around 7:30 a.m. to Saugus High School, about 40 miles north of Los Angeles, followed by anxious parents who had heard reports of a shooter at the campus.

"I hate to have Saugus be added to the names of Columbine, Parkland, Sandy Hook, but it's a reality that affects us all throughout the nation," Los Angeles County Sheriff Alex Villanueva said.

The deceased students were identified as a 14-year-old boy and 16-year-old girl. Three other victims remained hospitalized.

Villanueva said the 16-year-old shooter, who used a .45 caliber semi-automatic pistol to shoot his classmates and then himself, was transported to a hospital in grave condition. He shot himself in the head, Villanueva said.

Multiple law enforcement sources told the NBC4 I-Team that the shooter, identified as Nathaniel Tennosuke Berhow, was brain dead and not expected to recover.

Berhow was originally described as a 15-year-old boy, but it was later revealed that the shooting occurred on his birthday Thursday.

The entirety of the shooting lasted 16 seconds.

Officials said in a news conference that the shooter was captured on camera reaching into a backpack, shooting five students, and then shooting himself.

"From the time that he withdrew the handgun from his backpack to the time he was on the ground with a gunshot wound to his head, was about 16 seconds," Capt. Kent Wegener of LASD Sheriff's Homicide Bureau said.

When first responders converged on the school's outdoor quad, they found multiple injured students, including the suspected shooter. They all were scooped up and taken to the hospital in the chaos of the situation.

School Shooting Incidents Since 2013

Everytown.org defines the incidents mapped below as any time a firearm discharges a live round inside or into a school building or on or onto a school campus or grounds, as documented by the press and, when necessary, confirmed through further inquiries with law enforcement or school officials. Incidents in which guns were brought into schools but not discharged are not included.

Source: Everytown.org, NBC Staff Reports

Last updated on Nov. 14, 2019

LA County Fire Chief Daryl Osby said officials discovered six injured people suffering from gunshot wounds; the most critical was one found shot in the head, another in cardiac arrest.

Detective Daniel Finn of the Santa Clarita Sheriff's station had just dropped off a family member at the school and was driving away when he saw children running away from the sound of the gunfire, Villanueva said.

"And he turned around and became the very first person on scene," he said. "They entered the school literally within seconds of the shooting."

The victims were all Saugus students, according to officials. Two of them, a 16-year-old girl and a 14-year-old boy, died later at the hospital. The other injured victims were described as a 14-year-old girl, a 15-year-old girl and another 14-year-old boy, Capt. Kent Wegener of the sheriff's homicide bureau said.

One victim was in stable condition at Henry Mayo Newhall Hospital, and one was released, Dr. Larry Kidd said.

The weapon the shooter used was recovered at scene. It had no rounds left in it, Wegener said.

Aerial video showed students with hands raised being escorted by deputies from the school of about 2,300 students. They were taken to school buses with armed deputies on board.

"The impact this is going to have not only on school but community is tremendous," LA County supervisor Kathryn Barger said. "Many of the sheriffs and fire officials who work here, live here, and either have children who attended this school or (currently) attend this school. So this hit very, very, very close to home."

Student Malena Peters was running late, accompanied by her mom as she arrived to a stunning scene at the school.

"We just see all of these students, running out and screaming," Malena said. "I never thought it would actually happen."

Malena's brother and a cousin were in the school during the search for the shooter. Both are OK, she said.

Student Sharon Orelana Cordova said she took cover under a table in a nurse's office until officers came to get her.

"When I got out, I saw this person lying on the ground with blood all over," she said.

Nearby residents were urged to lock their doors and remain inside during the search for the shooter, which extended from the campus to a nearby neighborhood. Authorities said later Thursday that the shooter was no longer considered a threat.

Several patrol vehicles were seen in a neighborhood near the school, where deputies with guns drawn were positioned outside a house.

"It's one of my worst nightmares as a sheriff," Villanueva said.

There was no immediate word on a motive. The suspected shooter's girlfriend and mother were both at the sheriff's station, speaking to authorities.

"That's going to take us a while to go through," Villanueva said.

Undersheriff Tim Murakami said rumors that the shooter posted threats on social media will be investigated.

Distressed parents arrived at the high school looking for their children.

"It's a great school and a great community, and we never thought something like this would've happened here," a mother told NBC4.

Central Park on Bouquet Canyon Road was being used for a family reunification center.

"I’m a 52-year resident of Santa Clarita, and I grew up in the Saugus area. We need to say no more. As the FBI special agent said, this is a tragic event, and it happens too frequently. Across the nation I hear frequently, ‘no more, no more, no more.'

"When are we going to come together as a community in Santa Clarita, and the rest of the communities, to say 'no more?'" Capt. Robert Lewis of the Santa Clarita Sheriff's Department said.

White House spokesman Judd Deere said President Donald Trump was monitoring the reports.

The Centre located at 20880 Centre Pointe Parkway will be open from 5-7 p.m. for families and community members who need support, per the city of Santa Clarita.

All schools in the Hart School District were to be closed Friday, Nov. 15, per a district spokesperson.

Two churches were holding services for the community to gather and mourn.

NBCLA's Heather Navarro and the NBC4 I-Team's Eric Leonard contributed to this report.