The three people in the apartment were among the six left dead Friday night during the shootings near the campus of the University of California, Santa Barbara. Elliot Rodger, 22, the suspected gunman, apparently killed himself, authorities said.
At a news conference, Sheriff Bill Brown called it a "chaotic, rapidly unfolding convoluted incident" that involved multiple crime scenes.
Police provided new details about the scope of the killings as they described how he went from one location to another and opened fire on random people and exchanged gunfire with law enforcement before he crashed his BMW. Brown said the suspect had more than 400 rounds of unspent ammunition in his car.
Brown identified Rodger as a student at Santa Barbara City College.
Shooting Through CommunityRodger fired for 10 minutes as he made his way through the beach community of Isla Vista where students were walking, biking and skateboarding in a deadly rampage that chillingly mirrored threats made on a YouTube video posted that same night, authorities said.
Seven others remained hospitalized with serious injuries.
Authorities confirmed Rodger was the shooter and said they had seized a semi-automatic handgun. It wasn't immediately clear whether he was killed by gunfire in two shootouts with deputies or if he committed suicide.
Investigators were analyzing a YouTube video in which a young man who identifies himself as Elliot Rodger sits in a car and looks at the camera, laughing often, and says he is going to take his revenge against humanity.
"It's obviously the work of a madman," Bill Brown said.
Earlier Saturday, Alan Shifman – a lawyer who represents Peter Rodger, one of the assistant directors on "The Hunger Games" – issued a statement saying his client believes his son, Elliot Rodger, was the shooter. It was unclear how the son would have obtained a gun. The family is staunchly against guns, he added.
"The Rodger family offers their deepest compassion and sympathy to the families involved in this terrible tragedy. We are experiencing the most inconceivable pain, and our hearts go out to everybody involved," Shifman said.
Richard Martinez said his son Christopher Martinez, 20, was killed in the shooting. He blamed politicians and gun-rights proponents. "When will this insanity stop? ... Too many have died. We should say to ourselves 'not one more,'" he said.
The shootings started around 9:30 p.m. in Isla Vista, a roughly half-square-mile community next to UC Santa Barbara's campus and picturesque beachside cliffs.
Alexander Mattera, 23, said his friend Chris Johnson was walking out of an improv comedy show when he was shot in front of a popular pizza place. He stumbled into a nearby house.
"He walked into these random guys' house bleeding," he said.
Thought Gunshots Were FirecrackersMattera was sitting at a bonfire with friends when at least one gunshot whizzed overhead. The friends ran for cover when they heard the barrage of gunfire.
"We heard so many gunshots. It was unbelievable. I thought they were firecrackers," he said.
Describing the shootings as "premeditated mass murder," Brown said a YouTube video posted Friday that shows a young man describing plans to shoot women appears to be connected to the attack.
UC Santa Barbara senior Kyley Scarlet said she heard the BMW smash to a halt outside a house she was in.
"We ran outside and saw a bicyclist had been hit," she said. "Then the police dragged a body out of the car. It was him," she said.
As vice president of student government, Scarlet said she called a UCSB associate dean of student to advise her a student may have been hurt.
Scarlet, who is a former sorority president, said two girls from a sorority next door were killed on the lawn of Alpha Phi, where a pile of flowers grew on Saturday. Crying students wandered up to the spot, shook their heads and hugged each other.
Scarlet said a third sorority member was wounded there as well. She said all three were in the same sorority, which she did not identify. She said they were neither in her sorority nor in Alpha Phi.
Scarlet said she was very disturbed by the video describing his anger at sorority girls.
"It's hard thinking my actions, being part of a sorority, led him to do this," she said. "When I saw that video I was shaking and crying."
In the video, Rodger describes loneliness and frustration because "girls have never been attracted to me," and says, at age 22, he is still a virgin. The video, which is almost seven minutes long, appears scripted. The identity of the person in the video could not be independently confirmed.