LOS ANGELES (AFP) - A former US cop wanted for multiple murders was reported dead on Tuesday in a burning mountain cabin, after a six-day manhunt that jangled nerves in southern California and beyond.

Christopher Dorner's body was found inside the cabin near the California ski resort of Big Bear, where he had barricaded himself in after a shootout with police that left one officer dead and injured another.

The embittered 33-year-old had allegedly already killed three people before going on the run last week, after posting a chilling online manifesto threatening to kill more officers.

He was cornered in the snow-covered San Bernardino mountains after nearly a week-long manhunt, which focused on Big Bear before expanding amid reported sightings elsewhere in California and a suggestion that he had fled to Mexico.

The LA Times said a single shot was heard as police moved in on the cabin, suggesting Dorner may have taken his own life, although that was not immediately confirmed.

Officers broke the cabin windows, pumped in tear gas and called for Dorner to surrender over a loudspeaker, the LA Times said. When they got no reply, they deployed a vehicle to rip down the cabin walls.

It did so "one by one, like peeling an onion," a law enforcement official told the newspaper. When it got to the last wall, a single gunshot was heard, before flames began to spread through the structure.

NBC and local KTLA 5 television both reported that a body believed to be Dorner's had been found in the cabin.

KTLA 5 television cited LA Police Department (LAPD) spokesman Commander Andrew Smith as saying: "We believe he is dead. We believe he was in that cabin. We believe he was burned up in that cabin."

Police launched a massive manhunt last week for Dorner, after he allegedly killed a couple and a policeman, and injured another three officers, while pledging online to kill officers in revenge for his 2008 sacking.