The extraordinary manhunt for an ex-LAPD officer suspected of three killings converged Tuesday on a mountain cabin where authorities say he barricaded himself inside, engaged in a shootout that killed a deputy and then never emerged as the home went up in flames.

A single gunshot was heard from within before caught fire, and a charred body was found inside, sources told The Associated Press.

A tweet posted by the LAPD denied that, saying a body was not "located, removed or identified from the location in San Bernardino." 

If the suspect involved in the standoff was 33-year-old Christopher Dorner, the search for the most wanted man in America over the last week has ended the way he predicted in an online manifesto — death, with the police pursuing him.

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San Bernardino Sheriff's Department spokesperson Cindy Bachman says police have ‘reason to believe’ the suspect involved in Tuesday’s shootout and cabin fire is Christopher Dorner. (Kevork Djansezian/Getty)

Thousands of officers had been on the hunt for the former Navy reservist since police said he launched a campaign to exact revenge against the LAPD for his firing. In an online rant, Dorner threatened to bring "warfare" to police officers and their families, spreading fear and setting off a search that stretched across the American Southwest and into Mexico.

"Enough is enough. It's time for you to turn yourself in. It's time to stop the bloodshed," LAPD Cmdr. Andrew Smith said at a news conference held outside police headquarters in Los Angeles on Tuesday.  

Shortly after, smoke began to rise from the cabin in the snow-covered woods near Big Bear Lake, a resort town about 128 kilometres east of Los Angeles. Flames then engulfed the building — images that were broadcast on live television around the world.

 TV helicopters showed the fire burning freely with no apparent effort to extinguish it.

"We have reason to believe that it is him," said San Bernardino County sheriff's spokeswoman Cynthia Bachman, adding that she didn't know how the fire started. There was gunfire between the person in the cabin and officers around the home before the blaze began, she said.

Until Tuesday, authorities didn't know whether Dorner was still in the Big Bear area, where they found his burned-out pickup last week.

Stolen vehicle led to standoff

Big Bear Lake California

Around 12:20 p.m. local time Tuesday, deputies got a report of a stolen pickup truck, authorities said. The location was directly across the street from where law enforcement set up their command post on Thursday and not far from where Dorner's pickup was abandoned. The owner of the vehicle taken Tuesday described the suspect as looking similar to Dorner.

A warden for the California Department of Fish and Wildlife travelling down Highway 38 recognized a man who fit Dorner's description travelling in the opposite direction. The officer pursued the vehicle and there was a shooting at 12:42 p.m. local time in which the wildlife vehicle was hit numerous times and the suspect escaped on foot after crashing his truck.

After holing up in the cabin, there was a second gunbattle with San Bernardino County deputies, two of whom were shot. One died and the other was expected to live after undergoing surgery.

"We're heartbroken," Big Bear Lake Mayor Jay Obernolte said of the deputy's death and the wounding of his colleague. "Words can't express how grateful we are for the sacrifice those men have made in defence of the community and our thoughts and prayers are with them and their families."

The man believed to be Dorner never came out of the cabin, and a single shot was heard inside before the cabin was engulfed in flames, a law enforcement official told The Associated Press.

The official later told the AP that a charred body was found in the burned cabin. The official requested anonymity because of the ongoing investigation.

Officials were waiting for the fire to burn out before approaching the ruins to search for a body.

Police say Dorner began his run on Feb. 6 after they connected the slayings of a former police captain's daughter and her fiancé with an angry Facebook rant they said he posted. Threats against the LAPD led officials to assign officers to protect officers and their families.

After police release Dorner’s photo and described him as armed and "extremely dangerous," Dorner allegedly tried to steal a boat in San Diego to flee to Mexico. After that failed, he opened fire on two patrol cars in Riverside County — a suburban Los Angeles area city — shooting three officers and killing one.

Jumpy officers guarding one of the targets named in the rant shot and injured two women delivering newspapers Thursday in Torrance because they mistook their pickup truck for Dorner's.

Search focused on resort area of Big Bear

Police got a break when they discovered found weapons and camping gear inside the charred truck in Big Bear.

Helicopters using heat-seeking technology searched the forest from above while scores of officers, some using bloodhounds, scoured the ground and checked hundreds of vacation cabins in the area.

A snowstorm hindered the search and may have helped cover his tracks, though authorities were hopeful he would leave fresh footprints if hiding in the wilderness.

Dorner remained in hiding until today.