Authorities heard a single gunshot as they prepared to rip down the final wall to the cabin in which its believed fugitive former LA cop Christopher Dorner had holed himself up in, the Los Angeles Times has reported.
A law enforcement source told the newspaper police had smashed windows, fired tear gas into the cabin and called for Dorner to surrender with a loud speaker.
After getting no response, police used a vehicle to rip down the cabin's walls "one by one, like peeling an onion," according to the official.
The gunshot was then heard and flames quickly engulfed the battered cabin, the official said.
More top news
Freezing as temperatures fall
The royal couple ended a trip to the North East by visiting the new Northern Spire bridge, which stands twice as high as Nelson's Column.
A review has launched over concerns about the pregnancy test drug Primodos, vaginal mesh implants and anti-epilepsy drug sodium valproate.