Investigators found Dorner's truck abandoned and burning on a forestry road near Big Bear Lake, about 100 miles east of Los Angeles, San Bernardino County Sheriff John McMahon said.
The discovery spurred more officers to converge on the area to beef up patrols and go to every residence in the mountain community. Police searched at least 400 homes in the area.
February 8: Massive search in the mountains
The hunt for Dorner was "extremely dangerous," the San Bernardino County sheriff said, as SWAT teams used snowcats to zoom up a mountain and other officers prowled forest roads in an armored personnel carrier.
"We're going to continue searching until we either discover he left the mountain or we find him," McMahon told reporters at Big Bear Lake.
Elsewhere, U.S. Navy installations throughout California and Nevada were "maintaining a heightened security posture," a U.S. military official told CNN.
February 8: Plenty of weapons
Guns found in the burned truck were also burned, but authorities believe Dorner may have had up to 30 guns with him, said a source with knowledge of the investigation. Dorner was trained in counterinsurgency and intelligence in the Navy, the source said.
In La Palma, California, police searched the home of Dorner's mother, and she and a daughter were cooperating with investigators, Irvine police Lt. Bill Whalen said.
February 8: No sighting of suspect
Authorities temporarily suspended their search until the following day, but expected to complete a search of more than 200 vacant cabins.
Overnight patrols were beefed up with 12 extra two-officer teams.
February 9: The search goes on
Bundled up in winter gear, search teams returned to the pine forests and trails surrounding Big Bear Lake in the San Bernardino Mountains.
Officers trudged through knee-high snow with rifles. Patrols again visited homes in Big Bear Lake, knocking on doors and peeking into windows.
February 9: Police to review Dorner complaint
Los Angeles police announced the department would reopen the investigation into the case that led to Dorner's termination.
"I do this not to appease a murderer," Chief Beck said in a statement. "I do it to reassure the public that their police department is transparent and fair in all the things we do."
Police vowed they would catch Dorner and urged the former officer to turn himself in.
In Big Bear Lake, resident Justin Owen said police asked him whether he had seen suspicious activity. No, he told them.
"I don't think he is up here, to be quite honest with you, in this quite brutal weather," Owen told CNN.
But his father, Ed Owen, said he thought Dorner may have been hiding in any of the houses that serve as second residences in the mountains and are often vacant.
"I would guess the occupancy rate on my block is just 10%," he said.
February 10: A $1 million reward
Los Angeles Mayor Antonio Villaraigosa announced a $1 million reward for information leading to Dorner's arrest and conviction. The reward includes funds from businesses, private donors and community groups.