A storm pounding southern and central California reportedly killed at least four people overnight on Friday, causing flash floods and forcing the evacuation of hundreds of people from their homes.
Los Angeles city fire officials said a 55-year-old man was electrocuted after a tree downed a power line.
Several people stranded near the Los Angeles River had to be rescued with inflatable boats.
Two other people died in car accidents in the San Diego area, and a fourth was died in a submerged vehicle, local media reported.
Another person was injured after her car fell into a massive sinkhole in Los Angeles, local television station KABC reported.
She was trapped until fire crews pulled her out.
The powerful storm blew in from the Pacific Ocean, hitting California on Friday with high winds and heavy rain that downed power lines, leaving 60,000 people in the Los Angeles area without power, and prompting hundreds of flight delays and cancellations at airports.
Rushing flood waters swept away cars, downed trees and caused mudslides and sinkholes, the National Weather Service (NWS) said.
Flash-flood warnings will continue through the weekend in many areas of the West Coast state, which has been hit this winter by a series of storms that have filled reservoirs, bringing respite following a severe five-year drought.
Although the latest storm, which packed heavy wind-driven rain, was mainly affecting southern and central California, rain was also forecast to hit the San Francisco Bay Area in the north.
The downpours in other heavily populated areas of southern California, including parts of Santa Barbara and Ventura counties also recently hit by wildfires, could create the risk of mud and debris flows there too, the weather service said.
Authorities have warned residents of an area west of Santa Barbara, where another wildfire ravaged vegetation last year, to prepare to leave their homes quickly if ordered to evacuate.
Rain also battered parts of Northern California and southern Oregon and the weather service had flood warnings in effect in both regions.
In higher areas of eastern California and western Nevada, as much as 60cm of snow could cause whiteouts, forecasters said.
Southwest Airlines said it had cancelled more than 250 flights in California. Airports in Los Angeles, San Francisco and other parts of California had dozens of cancelled or delayed flights, according to tracking website FlightAware.com.
Residents of the city of Duarte, located in the foothills of the San Gabriel Mountains east of Los Angeles, were ordered to evacuate on Friday for fear of mudslides and voluntary evacuation orders were issued for some residents of Camarillo Springs, north of Los Angeles.
Duarte resident Alberto Moreno, 34, piled sandbags outside his home on Friday after refusing to leave the area.
“The neighbours are here so we’re all basically going to help out each other if it comes down to it,” Moreno said.
Heather Malone, 44, another Duarte resident, said she was prepared to escape by car if she saw “half the mountain coming down” near her home.
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