Five people have been killed by mudslides that swept southern California homes from their foundations as a powerful storm drenched wildfire-burned areas, authorities said.

Santa Barbara County Fire Department said the bodies were found in mud and debris during rescue operations in Montecito, north west of Los Angeles.

KEYT-TV showed a body being loaded into a military-style truck on a mud-covered street.

Captain Dave Zaniboni said “multiple” homes were destroyed and some residents are unaccounted for in neighbourhoods below hillsides scarred by recent wildfires.

Crews are clearing debris that closed a section of the US 101 highway along the border of Santa Barbara and Ventura counties.

Helicopters are being used to rescue residents as the storm drops record amounts of rain across the state because roads are blocked, Santa Barbara County spokeswoman Amber Anderson said.

Mud washes away personal belongings along La Tuna Canyon road in the Sun Valley neighbourhood of Los Angeles (David Crane/Los Angeles Daily News via AP)
Mud washes away personal belongings along La Tuna Canyon road in the Sun Valley neighbourhood of Los Angeles (David Crane/Los Angeles Daily News via AP)

“The primary issue right now is access. We’ve got trees and power lines down,” she said.

Evacuation orders were issued on Monday as forecasters predicted mudslides in foothill neighbourhoods where the state’s largest-ever fire raged last month.

“We’re performing multiple rescues. There will be more,” Capt Zaniboni said, adding that some of those taken to safety had been buried in mud.

The first significant storm of the season hit much of the state with damaging wind and thunderstorms.

Mud flows leave a van stuck in the mud along La Tuna Canyon road in the Sun Valley neighbourhood of Los Angeles (David Crane/Los Angeles Daily News via AP)
Mud flows leave a van stuck in the mud along La Tuna Canyon road in the Sun Valley neighbourhood of Los Angeles (David Crane/Los Angeles Daily News via AP)

Record-breaking rain fell on the San Francisco Bay region before the system largely passed overnight, leaving diminishing showers before dawn.

Stormy weather continued to the east in the Central Valley and Sierra Nevada.

Central San Francisco had 3.15in of rain, smashing the old mark of 2.36in set in 1872 and making it the city’s 16th wettest day since 1849, the National Weather Service said.

Firefighters respond to mud and debris flow due to heavy rain in Montecito. California (Mike Eliason/Santa Barbara County Fire Department via AP)
Firefighters respond to mud and debris flow due to heavy rain in Montecito. California (Mike Eliason/Santa Barbara County Fire Department via AP)

To the south, a staggering 9.6in 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 more rain to central 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 at both ends of the state.