Los Angeles (CNN) -- Authorities on Saturday identified a gunman killed by police after he opened fire at passing vehicles along a downtown street in Hollywood.
But they said they don't know why Tyler Brehm, 26, went on a surreal shooting rampage captured on amateur video Friday.
The video shows Brehm walking down Sunset Boulevard, wielding a handgun and firing at vehicles, seemingly at random. Brehm fired a "significant number" of rounds, wounding three, police said.
He then returned to an intersection, where he was confronted by a plainclothes police detective and an off-duty police officer working on a nearby movie set, officials said.
"At that point the police ordered him to drop his weapon and he pointed his gun at the police and an officer-involved shooting occurred," police spokeswoman Sgt. Mitzi Fierro said on CNN.
Brehm died at a nearby hospital, a police statement said.
Christopher Johns filmed much of the five-minute scene from his apartment window and can be heard shouting at Brehm throughout.
"Why don't you come up here?" he yelled, later describing that he intended to distract the gunman.
"If people down there at point-blank range to the shooter were going to get shot, they were helpless to avoid being killed," Johns told CNN. "Me, I'm four stories up. If I can take any of his attention and divert it towards me ... I would have an opportunity to get out of the way."
"I'm screaming anything I can" in an effort to disrupt the shooting, Johns said.
At one point, Brehm spoke with Johns, asking him for ammunition and to call an ambulance.
Fierro said it appeared Johns could interact with the suspect without jeopardizing his safety.
"It appears from the video that he was able to distract the suspect and keep him from shooting at additional people before the police arrived," she said.
Police have contacted Brehm's family back east and are talking to acquaintances.
"So far we haven't been able to piece together really why he did it," Fierro told CNN Saturday evening.
Three people were injured during Friday's incident, including one man in silver Mercedes-Benz sedan who was shot multiple times in the face and upper torso, Fierro said. Two others suffered minor injuries.
The current status of the man in the car was unknown Saturday.
"We're very fortunate that more people weren't injured during this incident," Fierro said.
Witnesses were stunned by the shooting rampage.
"A car drove by and he just shot right into the car," Amy Torgeson told CNN affiliate KABC. "He was just shooting everywhere."
Torgeson said vehicles began "swerving and braking," and she sought cover at a nearby bank.