One passing motorist, a music industry executive, was shot in the face by the gunman Friday and remained in critical condition Saturday.
Los Angeles County Coroner's Lt. Larry Dietz said Brehm's body would be examined later in the day.
Brehm walked down the middle of Sunset Boulevard, firing on motorists with no clear target and injuring three of them until two police officers who just happened to be in the area - an off-duty motorcycle officer working movie set security and an LAPD detective - shot and killed him, authorities said.
Investigators were trying to determine a motive for the attack.
Christina Mesropian, who described herself as a friend and neighbor of Brehm, said he was distraught over a breakup with his longtime girlfriend. She said the two lived together in her apartment complex.
"He wasn't a bad guy, he just got fed up," Mesropian told KNBC-TV. "He was like `Ah, I'm over it, I'm over it,' but I could tell he wasn't over it."
Brehm's girlfriend, Alicia Alligood, did not appear on camera, but told a KNBC reporter only that she and Brehm had "been dating for four and a half years, we broke up recently."
Ramon Hernandez, who lived in the apartment next door to Brehm, said the couple had recently moved out. He told KABC-TV that they kept to themselves but he at times heard them arguing.
"I could tell that he was an unstable person," Hernandez said, "but I don't know the details on what actually made him snap."
In amateur video taken at the shooting scene, the gunman appeared to have short hair and wore jeans and a white tank top. He paced back and forth near the busy intersection with Vine Street, firing close to 20 rounds from what appeared to be a .40 caliber handgun, police said. Several witnesses reported seeing him reload at least once.
"He was screaming he was going to die and that he wanted to die," Gregory Bojorquez, a photographer who captured images of the shooting's aftermath, told the Los Angeles Times.
Chris Johns captured video of the gunman from his apartment window several stories above the street, and tried to distract and divert the gunman from shooting anyone on the street.
"Hey why don't you come up here! Come up here buddy!" Johns yelled.
Johns told KABC he saw a plainclothes officer shoot the man.
"I started shouting out to the officer, saying `take him out, that's the guy!"' Johns said.
He continued shooting at vehicles and in the air when he was confronted by the officers.
They ordered the suspect to stop and drop his weapon. He was shot when he pointed his weapon at the officers. The gunman was pronounced dead at the scene, Los Angeles police Officer Cleon Joseph said. No officers were hurt.
The area was cordoned off and the gunman lay under a white sheet in the street hours after the gunfire, leaving traffic tangled on busy Hollywood streets, an area packed with stores and restaurants.
The 40-year-old male driver of a Mercedes-Benz was wounded in the face and upper torso and taken to a hospital in "guarded and critical condition," police said in a statement.
The man, John Atterberry, was at Cedars-Sinai Medical Center and remained in critical condition Saturday night, hospital spokeswoman Simi Singer told The Associated Press.
Atterberry is a music industry executive who has worked with artists like Brandy, The Spice Girls and Jessica Simpson, according to the trade paper The Hollywood Reporter and other media outlets.
A truck and another car were struck by bullets.
Two people were treated at the scene for minor injuries. One man suffered a grazing wound to his left thigh when a bullet passed through his car door. Another man had minor cuts from broken glass after bullet struck the driver door where it met the window.
Associated Press writer Andrew Dalton contributed to this report.