The dramatic manhunt for fugitive ex-LAPD cop Christopher Dorner, who killed at least four people, apparently ended when the rural California cabin he holed up in went up in flames, with ammunition exploding in the inferno and smoke billowing up into the mountain air.

A source told the Associated Press that a charred body was found in rubble of the cabin. Sources told KTTV that the body appeared to be Dorner, but there was no official confirmation.

Dorner, who hours earlier had killed one San Bernardino sheriff's deputy and wounded another before barricading himself in the cabin, in the San Bernardino mountains, was believed to be inside. Dorner, who vowed not to be taken alive, had been surrounded inside the cabin since early Tuesday afternoon. It was not clear who set the fire in the Big Bear community where Dorner apparently has been hiding since sometime last week.

It was a stunning end to a saga that gripped the country, and had the nation's third-largest police department on tenterhooks for a week. Dorner, a former Navy man and highly trained marksman, had vowed revenge on the department he believed had wronged him - designating specific targets for death. As flames devoured the cabin, police stood by, confident that there was no escape for Dorner, and no way he could survive the blaze - assuming he had not already taken his own life. One law enforcement source told The Associated Press a single shot was heard inside the cabin before the fire broke out.

San Bernardino Sheriff Spokesperson Cindy Bachman told reporters that they will not enter the structure until it is safe to do so.

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Law enforcement sources said sometime within the last few days, Dorner broke into an cabin off Route 38, on the mountain resort area where days ago his truck was found burning. Two women were held there until Tuesday morning, when Dorner left in a white pickup believed to belong to one of the women, who he left bound inside. One managed to escape and call authorities around 12:50 p.m. local time.

Sometime later, fish and wildlife officers spotted the stolen pickup, which they were looking for, and tried to stop it near Big Bear Lake, authorities said. The driver, believed to have been Dorner, fled on foot, exchanging gunfire, sources told Fox News. Hours later, police had Dorner cornered in another cabin, exchanging gunfire with the suspect. It was there that his rampage would end.

As the forces surrounding the cabin mounted, the San Bernardino Sheriff's Department shut down Highway 38 to create a choke point, sources told Fox News. Four area schools were on lockdown.

The police also asked the media to stop tweeting events in real time and showing live aerial shots of the cabin, theorizing Dorner could be monitoring events on television. A CBS correspondent briefly found himself in the crossfire as he broadcasted from the event, before police ordered him out of the danger zone.

The shootout came after a day of searching and speculation, with authorities continuing their door-to-door search in the rural Southern California community, even as sources guessed Dorner, 33, may have made it over the border and into Mexico.

The hulking suspect, who claimed in a rambling manifesto posted online that he was booted from his job unfairly after official determined he falsely accused his partner of assaulting a suspect, vowed to being "asymmetrical warfare" to the department, using his police and military training, and named 40 "targets." Police have guarded the homes of the targets even as they conducted what may be the biggest manhunt in state history.

Dorner was suspected of gunning down Monica Quan, 28, and her fiancé Keith Lawrence, 27, on Feb.3 in a parking garage in Irvine, Calif. Quan’s father, Randall Quan, represented Dorner at the hearing in which he lost his job in 2009. On Monday, a day after Quan and Lawrence were found dead, some of Dorner's belongings were discovered in a trash bin near San Diego. Dorner’s bizarre manifesto surfaced on Facebook, implicating him in the murders and announcing his twisted plan for revenge against his former employer. Police hunted Dorner in San Diego, where last Wednesday night a man matching his description tried unsuccessfully to steal a boat from a marina there.

In the wee hours on Thursday, some 100 miles north in Riverside County, two LAPD officers assigned to protect a person named in Dorner’s manifesto chased a vehicle they believed was Dorner's. During an ensuing shootout, one officer was grazed in the forehead. Moments later, a gunman believed to be Dorner ambushed two Riverside cops at a traffic light, killing 11-year veteran Police Officer Michael Crain and critically injuring the other.

Dorner’s burning truck turned up 50 miles west of Riverside later that morning. Although statewide alerts were issued in California and Nevada, and authorities were watching the border, the most intense phase of the search has not left Big Bear since the truck was found on a local forest road.

In recent days, hundreds of police officers scoured the mountain, searching cabins door-to-door. While the search on Big Bear was scaled back on Monday, the San Bernardino County Sheriff's Department continued the hunt, likely within a stone's throw of their violent quarry.

Meanwhile, an associate of Dorner was being tracked by investigators, according to court records that suggest Dorner may have received help as he eluded a massive law enforcement dragnet. A criminal complaint filed in federal court raises the possibility that Dorner may have been assisted by an associate identified as "J.Y."

The Associated Press contributed to this report.