Los Angeles police have launched a huge manhunt for a sacked officer suspected of killing three people, including a former colleague.
Christopher Dorner, 33, is alleged to have gunned down a policeman and wounded two others on Thursday morning.
He is also wanted over the shooting deaths of a couple at the weekend, the BBC reports.
Mr Dorner is said to have implicated himself in a 14-page "manifesto" that made threats against several people, including Los Angeles police employees.
The former US Navy reservist was with the police department between 2005-08, but lost his job for making false statements.
He is accused of: shooting dead Monica Quan, 28, and her fiance Keith Lawrence, 27, on Sunday night in their car at their home in Irvine, California; shooting at two officers on Thursday morning in Corona, east of Los Angeles; and ambushing two policemen in their patrol car in the town of Riverside a few hours later, killing one and wounding the other.
Ms Quan's father, a retired policeman, represented Mr Dorner before a disciplinary tribunal that ruled against the suspect at the time of his dismissal.
According to court documents, Mr Dorner was fired in 2008 after making a complaint against his field training officer, saying she had kicked a suspect, a schizophrenic man with severe dementia, during an arrest.
The alleged victim's father gave testimony at a court of appeal that supported Mr Dorner's claim.
Officials have assigned more than 40 protection details to potential targets of the fugitive.