Updated at 4:37 p.m. ET
Two students have died after a gunman opened fire Thursday morning at Saugus High School in Santa Clarita, Calif., according to law enforcement officials. Three other students also were shot.
Authorities have not named the suspect but say he is a 16-year-old student at the school. He carried out the attack on his birthday.
At a midday news conference, Capt. Kent Wegener of the Los Angeles County Sheriff's Department's Homicide Bureau said detectives reviewed surveillance video footage from the high school that showed the suspect taking a handgun from his backpack and shooting five other people before shooting himself in the head.
The suspect is currently in "grave condition," Los Angeles County Sheriff Alex Villanueva said.
The sheriff's department says the victims who died are a 16-year-old female and a 14-year-old male, both of whom died at the hospital Thursday morning.
The others who were hospitalized include two more female students, ages 14 and 15, along with a second 14-year-old male student.
Wegener said the suspect, said to have been dressed in black, used a .45-caliber semiautomatic pistol that had no more bullets in it when it was recovered.
After receiving a report of shots fired at Saugus High, deputies found six students suffering from gunshot wounds in the school's quad. The wounded teenagers were triaged and transported to hospitals.
"The suspect was later identified as one of the victims who was found in the quad," Wegener said.
The teenager "is in custody and being treated at a local hospital," Villanueva tweeted. Investigators are still working to determine what could have led to the violence.
The FBI is also involved in the case; Wegener said the bureau will help recover any cellphone video that may have been captured during the attack.
He added that the suspect's mother and girlfriend are being interviewed at the Santa Clarita Valley Sheriff's Station. Authorities say they believe the suspect acted alone.
Four of the wounded students were transported to Henry Mayo Newhall Hospital, which says that three of them — two males and one female — arrived in critical condition. The female patient and one of the male patients later died, according to hospital spokesman Patrick Moody. Another male student was in good condition, he said.
The shooting took place before the start of classes, shortly after 7 a.m. local time. "Deputies responded to reports of shots fired," the sheriff's station said via Twitter. "This is an active shooter situation."
After deputies reached the school, they worked to clear the campus and begin a systematic search for the suspect on school grounds and nearby.
As first responders rushed to answer the call about an active shooter at Saugus High School, some of them were also contending with an added layer of pressure and anxiety: They have children who are enrolled there.
"There were several members of my department — and this is a very close-knit community — that had kids that were also at the school," Los Angeles County Fire Chief Daryl Osby said at the midday news conference.
Villanueva confirmed that some of his deputies also have children who are students at Saugus.
"This area has an awful lot of law enforcement presence," the sheriff said, "so it would not surprise me" if off-duty deputies had responded to the scene.
The school became the scene of a large evacuation as lines of students were led through its parking lot to a secured area. Officials set up a reunification point at Central Park, across a major roadway south of the school.
After the shooting, the fate of the suspect wasn't immediately known. In that interval, nearby residents were asked to "shelter in place and report any suspicious activity," said Tim Murakami, undersheriff of the Los Angeles County Sheriff's Department.
The shooting also prompted a lockdown order for nearby elementary schools. A broader lockdown was ordered for the entire William S. Hart Union High School District, but that was later rescinded.
"I hate to have Saugus be added to the names of Columbine, Parkland, Sandy Hook," Villanueva said, listing other horrible school shootings at the midday news conference. "But it's a reality that affects us all throughout the nation, something we're going to have to deal with."
He added, "We've got to figure out what are we doing wrong and how can we stop this from happening in the future."
This is a developing story. Some facts reported by the media may later turn out to be wrong. We will focus on reports from police officials and other authorities, credible news outlets and reporters who are at the scene. We will update as the situation develops.