SAN FRANCISCO -- Rain and snow falling across California have forced the closure of a major freeway, snarled commutes and triggered deadly wrecks on slick roads Wednesday as wildfire-ravished communities braced for dangerous mudslides and mountain residents faced a "potentially life-threatening" blizzard.
A series of storms have hit this week, and the latest one could be the strongest in Northern California.
"A powerful Pacific storm will hammer the West Coast into Friday with strong winds, heavy rain and heavy mountain snow," the National Weather Service said. "Heavy rain will bring a threat of flash flooding along recent burn scars while blizzard conditions are expected" in the Sierra Nevada.
Heavy snowfall and crashes shut down westbound Interstate 80 at the Nevada border, blocking one of the two routes to the Sierra Nevada and most of Northern California's ski resorts, authorities said.
In Southern California, fog on a mountain highway triggered a 19-vehicle crash. Thirty-five people were evaluated for injuries after the pileup on Interstate 15 in Cajon Pass, but most declined to be taken to hospitals, the San Bernardino County Fire Department said.
A mudslide on a major Northern California freeway just north of the Golden Gate Bridge disrupted the morning commute. The slide closed southbound Highway 101 across the bridge for about an hour, shutting off the only direct access to San Francisco for drivers north of the city.
Pacific Gas & Electric said about 10,000 customers lost power, most of them north of San Francisco.
In areas recently scarred by wildfires, authorities fear small rivers and creeks will flood their banks and cause massive mudslides, further damaging communities struggling to recover from a historically bad fire season.
The blazes stripped hillsides of trees and other vegetation that stabilize soil and prevent mudslides, putting at risk thousands of people living in foothill and canyon areas devastated by wildfires. That includes the Northern California region where a November fire killed 86 people and destroyed nearly 15,000 homes.
"If flooding occurs, this can quickly become a dangerous and life-threatening situation," the Butte County Sheriff's Office said.
Authorities told residents of Pulga to prepare to flee their canyon community that neighbors the town of Paradise, which was leveled two months ago by the Camp Fire.
People in the San Francisco Bay Area were warned to watch for flash floods through the end of the week. The Sacramento area faced flood and high wind watches, with gusts that could lead to power outages, downed trees and tough driving conditions.
Conditions started deteriorating on California roadways Tuesday night.
Three people, including an infant, were killed when their car spun out on a freeway in Placerville, about 130 miles (202 kilometers) east of San Francisco. Authorities blamed it on high speed and rain-slickened roads.
In the mountainous community of Truckee where it snowed Tuesday, residents were preparing for the next storm by clearing driveways and buying wood and food in case they have to stay inside.
"It took my husband an hour to get to Safeway last week because there were so many people and no one could get home," Whitby Bierwolf told the Sacramento television station KCRA. "You just need to have an alternate plan and have enough stuff in your car because accidents happen."
The Sierra Nevada and Lake Tahoe regions could see up to 5 feet (1.5 meters) of snow.
In the south, some evacuation orders were in place in the Malibu area west of Los Angeles and parts of neighboring Ventura County. Both were affected by a November fire that destroyed more than 1,500 homes and killed four people.
Paul Manion was busy filling sandbags in the community of Bell Canyon.
"It's something we have to do. I mean, if the water comes, it comes," Manion told KABC-TV. "Everything around our house burned. All the houses around our house burned. But it's the hillsides that we're worried about."
Others refused to leave after authorities went door to door at the high-risk Paradise Cove mobile home park in Malibu. Beaver Valenzuela said he's survived fiercer storms and wouldn't leave until he was convinced the danger was more immediate.
"I'm not going anywhere," he told the Los Angeles news station.