BIG BEAR LAKE, Calif.: A fugitive former police officer accused of declaring war on law enforcement in an Internet manifesto and wanted as a suspect in three murders eluded a manhunt for a second day on Friday in the snow-swept mountains east of Los Angeles.

Search teams combed hillsides and homes around a ski area through the night and past daybreak for Christopher Dorner, 33, a former Navy officer presumed by police to be heavily armed and intent on carrying out a vendetta against those he blames for his 2008 dismissal from the Los Angeles Police Department.

"We did not find any additional evidence, and we certainly did not locate him," San Bernardino County Sheriff John McMahon told a news briefing, adding that investigators were pressing ahead despite heavy snow that complicated the manhunt.

"We're going to continue searching until either we determine that he's left the mountain or we find him," McMahon said at the Big Bear Lake resort, about 80 miles (130 km) northeast of Los Angeles.

The snowfall grounded helicopters used on Thursday to scour the area with infrared cameras. But a team of more than 100 law enforcement officers, some of them riding on "snow cat" tractor vehicles, kept up an intense ground search with dogs.

The search focused on a wooded area near where Dorner's pickup truck was found burning in the snow on Thursday, and in nearby higher elevations dotted with abandoned cabins, McMahon said. Search teams had followed footprints near Dorner's truck "around the forest ... until we lost them where the ground got frozen and we couldn't continue to track," he said.

By Friday morning, sheriff's deputies had gone door to door to several hundred vacation homes without finding signs of forced entry, and no vehicles were reported stolen. Area schools that were shut down on Thursday as a precaution remained closed due to snow, McMahon said.

As speculation mounted that Dorner might have slipped away undetected, police across the region continued to chase down unconfirmed sightings.

In downtown Los Angeles, a civilian employee of the Sheriff's Department reported seeing a man she thought resembled Dorner in a parking structure outside the city's main jail, prompting a lockdown of the facility while deputies searched the area, sheriff's spokesman Steve Whitmore said.

Police have said they believe Dorner was carrying multiple weapons, including an assault-style rifle, though the manifesto attributed to him suggested he might be more heavily armed.

"Do not deploy airships or gunships. SA-7 Manpads will be waiting," the message said, 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 (Los Angeles Police Department) uniform whether on or off duty," he allegedly wrote.

Police said they had taken steps to protect about 40 potential targets mentioned in the online declaration. The LAPD briefly canceled a citywide tactical alert, in which officers remain on their shifts and work overtime for as long as needed, but the alert was placed back into effect late Friday morning.

Dorner first came to public attention on Wednesday when he was named as a suspect in the weekend killings of a university security officer and his fiancée, college basketball coach Monica Quan, 28, in Irvine, about 40 miles (64 km) south of Los Angeles. They were found shot to death on Sunday in a car at the top of a parking structure.

Quan was the daughter of a retired Los Angeles police captain who represented Dorner in disciplinary action that led to his firing in 2008. Police say Dorner was dismissed for making false statements accusing another officer of using excessive force.

Two Los Angeles police officers assigned to a search detail traded gunfire with him early on Thursday in the city of Corona, east of Los Angeles, police said.

About 20 minutes later, two other officers were ambushed and one of them was killed. They had been sitting in their patrol car at a traffic light near Corona in the town of Riverside.

The officer who died, and whose name has not been released by authorities in an effort to protect his family from Dorner, was an 11-year Riverside police veteran. His wounded partner is expected to make a full recovery, police said.

Former Los Angeles Police Chief William Bratton warned on CBS television that the burned-out truck was "possibly a diversionary tactic to draw people into that area while he's actually heading south."

The FBI said its agents had searched a Las Vegas residence owned by Dorner, who joined the Navy in 2002 and the LAPD in 2005. He was discharged from the Navy Reserves last Friday, two days before Quan and her fiance were found slain.

Dorner, who once played college football, blamed the police department not just for firing him but also for ending his Navy career and the loss of close relationships.

He listed other grievances as well, such as encountering racism both at the LAPD and as an African-American boy growing up in Southern California.

But it remained unclear what led to the violence nearly five years after his firing and three years after his petition to be reinstated to the LAPD was denied by a judge.