He used his last bullet to shoot himself after targeting his school friends Thursday – the same day he was 16 years old. His motives remain a mystery.
Shortly before school began that day, the gunman walked to the campus area known as the quad, took a .45 caliber pistol from his backpack and shot at people nearby. Then he aimed the gun at himself.
Two students, Grace Anne Muehlberger, 15, and Dominic Blackwell, 14, died at the hospital, authorities said. Three other teenagers were injured and are expected to survive.
Chloe Rogers said that her friend, Muehlberger, had a cheerful personality and knew how to make her friends laugh.
"We will always share our silly jokes with each other, make Vine references, and laugh forever. His laughter is a laugh that will make you laugh harder. He always has something good to say and knows how to mess with his friends. I like it so much a lot and going to school knowing he wouldn't come to me randomly to talk is heartbreaking. "
Search for answers
The investigator delves into social media and the suspect's background. He was identified as Nathaniel Berhow and lived with his mother. His father died in 2017 due to natural causes.
There appears to be no connection between the shooters and the victims other than all students, the sheriff said.
"Nothing really stands out (with the suspect). He is not a loner. Not socially awkward. Involved in student activities. Student athletes," Los Angeles County Sheriff Alex Villanueva told CNN New Day. "This is rather sudden, to the surprise of many people who know him."
The shooter did not chase anyone during the shooting and appeared to randomly target the people around him, Villanueva said.
Saugus High School had active shooting practice just a few weeks ago, and faculty and students are doing exactly what they are training, he said.
An off-duty clerk rushed in to help
A detective who was not on duty took his girlfriend's son at Saugus High School when he saw hundreds of students running from campus Thursday morning. He was interesting and asked a student what was happening.
Someone shot, Detective Daniel Finn was told.
He and another officer not on duty found two of the five victims and the shooter was still on the ground in the quad. Finn said he saw the gun shooter but did not realize that one of the people treated was the shooter.
"My main concern is securing the scene, caring for the victims, and trying to ensure there are no additional shooters," Finn told reporters on Friday.
Finn, a former deputy of school resources now with the Los Angeles County Sheriff's Department, told an administrator to take medical aid bags from the school office. Officers who are not on duty third help treat the victims until medical assistance arrives.
Cheri Mossburg, Brian Ries, Jason Hanna, and Joe Sutton from CNN contributed to this report.