A motorist was fatally struck by a tree that was knocked by powerful winds as a winter storm hits California, bringing downpours, wind and snow, authorities said Sunday.

The driver was passing by a residential street in Pacific Beach when a large oak tree fell across a roadway, blocking all four traffic lanes, San Diego Fire and Rescue Capt. Joe Amador said.

The tree, which measured 8 feet in diameter, also crushed three parked cars that were not occupied, he said.

Strong winds downed dozens of trees and power poles and ripped off rooftops — and in one case, solar panels — across Southern California.

Wind gusts topped 65 mph in Malibu and 80 mph in the Angeles National Forest, according to the National Weather Service. The highest reading of the day was at Whitaker Peak, north of Castaic, where a gust was recorded at 115 mph.

The storm also dropped up to an inch of rain in some places by 4 p.m. Sunday, and forecasters said up to 2 inches of rain was expected in the valleys of Los Angeles County and as many as 3 inches possible for southwest-facing foothills and mountains.

Firefighters rescued a man trapped by the fast-rising Los Angeles River as the system moved in midmorning. The man was uninjured after being pulled to safety along the riverbank area east of downtown known for homeless encampments.

A flash flood watch was issued for foothill neighborhoods underneath wildfire burn areas, triggering fears of possible mudslides and debris flows. Scattered power outages were reported across greater Los Angeles.

Blinding rain briefly brought traffic to a near-standstill on LA freeways. North of the city, a crash during a heavy downpour involving two trucks closed southbound lanes of Interstate 5 near the Grapevine. There were no immediate reports of injuries. Motorists were warned to use caution on mountain roads, where snowfall above 5,500 feet could create icy conditions and poor visibility.

The storm also churned up high surf along west and northwest-facing beaches.

To the north, up to a foot of snow was expected to fall this weekend at the Sierra Nevada's highest peaks, the weather service said.

Another rain storm was expected in the San Francisco Bay Area by Sunday evening. A wind advisory was issued warning of winds gusting up to 50 mph.