A devastating storm billed by forecasters as the worst to hit California in years pounded the southern half of the state, wreaking devastation that claimed four lives, authorities said on Saturday.

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.

Emergency workers were forced to carry out numerous fast-water rescues after flash flooding forced hundreds from their homes, officials said.

Several people stranded near the Los Angeles River had to be rescued with inflatable boats.

Los Angeles city fire officials said the fatalities included a 55-year-old man who was electrocuted after a tree downed a power line.

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.

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.

Several inches of rain were forecast for parts of northern California.

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 LA.

Mudslides in the southern city of Santa Barbara forced Amtrak officials to suspend service between nearby Los Angeles and San Luis Obispo.

The National Weather Service said the northern part of the state -- where flooding last week damaged the Lake Oroville Dam and forced the evacuation of nearly 200,000 people -- was expected to see new rain and snow systems moving in during the next few days.

It forecast "the wettest storm" on Monday and Tuesday, warning of potential renewed flooding across Northern California.

"Recent storms have left the region highly vulnerable, so amplified impacts will be possible with additional rainfall," the NWS said.