Authorities say two people have been killed by a mudslide that has destroyed homes during a powerful Southern California storm.

Santa Barbara County Fire Department Capt. Dave Zaniboni says the bodies were found in mud and debris during rescue operations Tuesday in Montecito northwest of Los Angeles.

Zaniboni says several homes were swept from their foundations and residents are unaccounted for in neighborhoods below hillsides scarred by recent wildfires.

Crews are working to clear debris from a key stretch of U.S. 101 that was shut down along the border of Santa Barbara and Ventura counties.

Helicopters were being used even during the downpours because roads were blocked, Santa Barbara County spokeswoman Amber Anderson said.

"The primary issue right now is access. We've got trees and power lines down," she said.

She said "multiple" residents had been rescued and more were calling for help in Montecito and Carpinteria. Thousands were without power. Evacuation orders were issued Monday over fears of mudslides in those foothill neighborhoods where the state's largest-ever fire raged last month.

The first significant storm of the season soaked much of the state. Record-breaking rain fell on the San Francisco Bay region before the storm largely passed overnight, leaving diminishing showers there before dawn Tuesday. Stormy weather continued to the east in the Central Valley and Sierra Nevada.

Downtown San Francisco had a record 3.15 inches (8 centimeters) of rain on Monday, smashing the old mark of 2.36 inches (6 centimeters) set in 1872 and making it the city's 16th wettest day since 1849, the National Weather Service said.

To the south, a staggering 9.6 inches (24 centimeters) of rain fell on Mining Ridge on the Big Sur coast. Highway 1, still not recovered from last winter's damaging rains, suffered new blockages.

Forecasters issued flash flood warnings and predicted that the cold front with powerful winds could bring higher rain totals to downtown Los Angeles than recorded over the past 10 months. Mandatory evacuations were ordered for about 700 homes in former burn areas of Los Angeles County.

A winter weather advisory was in place for mountain areas, where officials warned motorists to prepare for difficult travel conditions, including gusty winds, low visibility and snow-covered roads

A years-long drought eased in the state last spring, but Northern California had a dry start to winter and hardly any measurable rain fell in the south over the past six months. The extremely dry conditions and high winds last year led to some of the most destructive blazes on both ends of the state.