A single gunshot was heard as authorities moved into the cabin where Christopher Dorner was believed to be holed up.
According to a law enforcement source, police had broken down windows, pumped in tear gas and blasted a loud speaker urging Dorner to surrender. When they got no response, police deployed a vehicle to rip down the walls of the cabin "one by one, like peeling an onion," a law enforcement official said.
By the time they got to the last wall, authorities heard a single gunshot, the source said. Then flames began to spread through the structure, and gunshots, probably set off by the fire, were heard.
Dorner's body has not been found. The police search will be focused in the basement area, the source said.