SANTA CLARITA, Calif. -- Three off-duty officers dropping off their children Thursday at a Southern California school rushed in seconds after gunfire erupted, quickly giving first aid and likely saving lives in a shooting that left two dead, authorities said.
The shooter opened fire at Saugus High School in Santa Clarita, killing two students and wounding three others before turning the gun on himself. The suspect -- a student at the school -- allegedly carried out the attack on his 16th birthday.
Two victims, ages 16 and 14, died at a hospital. The suspect is hospitalized in critical condition, authorities said.
One of investigators' largest tasks will be figuring out the motive, Los Angeles County Sheriff Alex Villanueva told CNN's "New Day" early Friday.
"There's nothing really that stands out (with the suspect). He wasn't a loner. Wasn't socially awkward. Was involved in student activities. Student athlete," Villanueva said. "This is kind of out of the blue, shocking pretty much everyone who knew him."
The weapon apparently jammed, sheriff says
The shooter walked into the school's quad area Thursday morning carrying a backpack. He retrieved a .45-caliber pistol without saying a word and fired one round, Villanueva said.
After shooting one student, he cleared a jam on the weapon and fired an additional four rounds at others, then himself.
"That ended it all in 16 seconds," the sheriff added.
It's unclear where the suspect got the gun, Villanueva said.
Officers entered the school within seconds
The first people at the scene were three off-duty law enforcement officers who were dropping off their children at the school, Villanueva said.
Detective Daniel Finn of the Santa Clarita Sheriff's Station was driving away when he heard gunshots and saw terrified children run out. He turned his car around and rushed into the school, the sheriff said.
Officer Sean Yanez of Inglewood police and LAPD's Gus Ramirez also rushed to the scene, Villanueva added. All three were off-duty and entered the school within seconds, he said.
"It's a tragedy every way you look at it, but there's a silver lining behind this: the fact that off-duty first responders were there and did not hesitate ... and they rendered first aid immediately," the sheriff said.
The officers saw a gun and figured the threat was likely over and focused on saving victims, he said.
The suspect has been identified as Nathaniel Berhow, two law enforcement sources told CNN. His father died in 2017 of natural causes, and he lived with his mother.
There appears to be no connection between the suspect and the victims other than all were students, the sheriff said.
"He wasn't chasing anyone," Villanueva said. The victims "appeared to be who was around him, available at the time."
Investigators are digging into his social media and background, he said.
Students hid in strangers' homes
Student Brooklyn Moreno was waiting for her first class to begin when the first shot rang out.
"Everyone thought it was a balloon, and it got really quiet. And then two more shots, and then everyone just ran out of the school," she told CNN affiliate KCBS. She ran across a street to someone's house until she was picked up.
Larry Everhart was leaving his house to get coffee when he saw screaming students sprinting down his street.
"They were saying, 'Can I come in your house?' It was about 20 of them. I wanted to make sure they were safe, so I got them in there," he told the affiliate.
Saugus High School has 2,400 students and is 30 miles northwest of Los Angeles.