* Suspect accused of killing three, wounding two
* Posted Internet manifesto threatening police
* Fugitive served in Navy (Adds latest comments from police)
By Steve Gorman and Dan Whitcomb
LOS ANGELES, Feb 7 (Reuters) - Police searched the mountains surrounding a California ski area on Thursday for a fired Los Angeles policeman accused of killing three people, after he declared war on law enforcement officers and their families in a rambling Internet manifesto.
The bloodshed attributed to Christopher Dorner, 33, began with the weekend slayings of a university safety officer and his fiancée, Monica Quan, 28.
She was the daughter of a retired Los Angeles police captain who represented Dorner in disciplinary action that led to his firing in 2008. Quan and her fiance were found dead in Irvine, some 40 miles (64 km) south of Los Angeles.
The violence escalated on Thursday with the fatal shooting of a police officer in Riverside and the wounding of two others.
Dorner's pickup truck was later found burning in the snow near the mountain resort of Big Bear Lake, 80 miles (129 km) northeast of Los Angeles. Investigators, who are now searching with air units and dogs, found tracks leading away from the truck, but they did not lead to the suspect.
"There's snow on the ground in a lot of the areas they're searching, and it's dark," Cindy Bachman, a spokeswoman for the San Bernardino County Sheriff's Department told reporters at Big Bear Lake. "It's very difficult to search in these conditions."
Bachman said schools and a ski resort in the Big Bear Lake area would re-open on Friday amid speculation Dorner might have left the area.
"I can tell you now that they have been searching for many hours and they have not found him," Bachman said.
Dorner, who joined the Navy in 2002 and the LAPD in 2005 and was a naval reservist until Friday, had posted his grievances on Facebook in what police see as a potential hit list. Police have taken steps to protect some 40 potential targets.
"This is a vendetta against all of Southern California law enforcement and it should be seen as such," Los Angeles Police Chief Charlie Beck told reporters.
"He knows what he's doing. We trained him. ... He was also a member of the armed forces. It is extremely worrisome and scary, especially to the police officers involved," Beck said.
The search for Dorner, a large man who once played college football, stretched at one time to San Diego - where he was believed to have tried to steal a boat on Wednesday night.
Two Los Angeles police officers assigned to a search detail traded fire with him earlier on Thursday in the city of Corona. One officer's head was grazed by a bullet, police said.
Two other officers were ambushed - one of them killed - about 20 minutes later while sitting in their patrol car at a traffic light in the adjacent town of Riverside, about 60 miles (100 km) east of Los Angeles. The officer who died was an 11-year Riverside police veteran. His partner was wounded but was expected to fully recover, police said.
Dorner was presumed to be armed with multiple weapons, including an assault rifle, Beck said, although his manifesto suggested he may be more heavily armed.
"Do not deploy airships or gunships. SA-7 Manpads will be waiting," Dorner wrote, in a reference to a Russian-made shoulder-launched missile system.
"The violence of action will be high. ... I will bring unconventional and asymmetrical warfare to those in LAPD uniform whether on or off duty.
"The attacks will stop when the department states the truth about my innocence," read the document, a copy of which was posted on Los Angeles television station KTLA's website but had been taken down from Facebook.
CNN reported that Dorner had also mailed a DVD and letter to on-air personality Anderson Cooper.
Dorner first came to public attention on Wednesday when he was named as a suspect in the slayings of Quan and her fiancé. Quan's father, retired LAPD Captain Randy Quan, had represented Dorner in hearings that led to his firing for making false statements accusing another officer of using excessive force.
"I never had the opportunity to have a family of my own , I'm terminating yours," he wrote in a portion of his manifesto addressed to the senior Quan. (Additional reporting by Dana Feldman in Riverside, Brandon Lowrey in Big Bear Lake, Nichola Groom and Alex Dobuzinskis in Los Angeles, Marty Graham in San Diego and Daniel Trotta in New York; Writing by Steve Gorman; editing by Patrick Graham)