Santa Monica, California (CNN) -- The suspect in a shooting spree that left four people dead in Santa Monica has been identified as John Zawahri, sources told CNN.
Authorities say he killed his father, Samir "Sam" Zawahri, and brother, Chris Zawahri, in a Santa Monica house before carjacking a woman and firing at a public bus on Friday.
Scant details are trickling in about Zawahri, who was killed by police at Santa Monica College on Friday -- the day before his 24th birthday.
The superintendent of the Santa Monica-Malibu school district said Zawahri attended a high school for students behind in academic credits in 2006.
"We are shocked and deeply saddened by the tragedy that so far has taken five lives and, once again, shatters our nation's confidence," Superintendent Sandra Lyon said.
Police had contact with the gunman in 2006, but because he was a juvenile then, authorities couldn't release further information, Santa Monica Police Chief Jacqueline Seabrooks said.
A law enforcement source with knowledge of the investigation told CNN on Saturday that the gunman had suffered mental health issues. A few years ago, he was hospitalized for treatment after allegedly talking about harming someone, according to the official.
It's not clear whether the state government or his family committed him for treatment or whether he committed himself. It's also unclear under what circumstances he was released.
Authorities have found no link to domestic or international terrorism, the official added.
Authorities believe the house was set on fire before Sam and Chris Zawahri were shot.
The following 13-minute shooting spree spanned several parts of Santa Monica.
The gunman and a family member had been enrolled in Santa Monica College as recently as 2010.
One of the four people killed was shot outside the library of the school, college Police Chief Albert Vasquez said. That woman's name has not been released.
Another victim, 68-year-old Carlos Navarro Franco, was driving an SUV on campus when he was gunned down, police said.
Franco was with his youngest daughter, Marcela, who was going to buy textbooks for her studies at California State University, Dominguez Hills, Santa Monica College President Chui Tsang said in a statement Saturday.
The 26-year-old daughter was shot and is in critical condition at Ronald Reagan UCLA Medical Center. She "is not expected to survive," Tsang said.
The assailant dressed in black and carried an assault-style rifle. Seabrooks estimated the gunman had about 1,300 rounds of ammunition during the rampage. Because he was wearing a ballistic vest and was heavily armed, "I would say it's premeditated," she said.
His apparently random gunfire became the nation's latest disturbing killing spree, ending with his death in the college library and leaving this tourist beachfront city reeling with shock.
Investigators are still trying to determine the motive in the shootings that also left five people wounded.
Jerry Cunningham stepped onto her porch when she heard the shots. She saw the gunman firing at a neighboring house that was on fire.
She then saw the gunman force a woman to stop her car at gunpoint.
Another car approached. The gunman waved it by, Cunningham said. That driver, also a woman, hesitated for just a moment, and the gunman "fired three shots directly into her and the car," Cunningham said.
The motorist was wounded in the shoulder, she said. Authorities said that driver was hospitalized and is in stable condition.
The gunman then got into the first car and forced the woman to drive off with him, police said.
During their ride, 911 calls poured in, keeping police on the gunman's path, Santa Monica police Sgt. Richard Lewis said.
As the car headed toward the campus of the community college, where 30,000 students are registered, he opened fire on a passing bus, slightly wounding three people, Lewis said.
He was carrying an "AR-15 style rifle," pistols and more clips for the rifle, Lewis said.
As the car pulled onto the campus, the man fired into Franco's red SUV, killing him and critically wounding his daughter, police said. Franco's vehicle crashed after the shooting.
The gunman then abandoned the hijacked vehicle -- leaving the driver unhurt -- and fled on foot, shooting at police, Lewis said.
Inside a classroom
Jasmine Franco, 22, was in a classroom at Santa Monica College -- next to the library -- waiting for her English class to start at noon on Thursday. Little did she know that the gunman began his rampage at a house near to where she lives with her mother, Carmen.
Jasmine Franco's friend had left the room to fill his water bottle and she was sitting alone when she first became aware something was wrong.
"You could hear rumbling, a lot of rumbling," she said, describing the sounds of gunfire mixed with the stampede of people running. "It sounded like an earthquake or something,"
But her 11 classmates and the teacher appeared oblivious, and continued their banter until her friend burst back in. "His whole face was red and his veins were coming out of his neck.
"I'm entirely serious," Franco recalled him saying. "There's a shooter on campus."
He told the class he had heard a gun unload. "He said it just sprayed and unloaded tons of rounds," Franco said.
Not knowing what to do, "We just sat there."
The teacher left the classroom to see what he could learn and, moments later, ran back inside. "He says, 'They just unloaded a magazine.'"
With the exception of his the gunman's father and brother,, all of the other shooting victims were apparently chosen at random.