LOS ANGELES (AP) — Fast-moving floodwaters swept through California mountain communities and residents fled homes below hillsides scarred by wildfires as the third — and largest — in the latest series of storms brought a deluge Sunday and warnings about damaging mudslides.

The National Weather Service cautioned that the system was expected to gain strength into the evening and could be the strongest storm in at least seven years. California has been swamped during a wet winter that has brought plenty of rain and snow after years of drought.

Residents in rural Santa Cruz County watched helplessly Sunday as the San Lorenzo River spilled over its banks for the second time this month, sending muddy water and debris into yards and homes. No injuries were reported.

"This is the fastest I've ever seen this river move. It's already flowing under my house. I have maybe 2 feet of clearance before it's in my living room," Paradise Park resident Tammy Grove told the Sentinel newspaper.

Battalion Chief Aldo Gonzales with the Department of Forestry and Fire Protection said the river is the highest he has ever seen it.

Rock slides, debris flows and flooding closed roads and snarled traffic up and down the state as the third storm in four days dumped heavy rain and snow in the mountains.

Flash flood watches and warnings were in effect for swaths of greater Los Angeles, where mountain locations could see up to 6 inches of rain. Rain fell at a rate of nearly three-quarters of an inch per hour.

Traffic was diverted off Interstate 110 south of downtown Los Angeles because of water flowing across lanes.

Authorities ordered evacuations near wildfire burn areas in Santa Barbara, Los Angeles and Orange counties. Potential debris flows could restrict access for emergency responders, officials said.

Some residents refused to leave, but Ralph Olivas loaded up his family and their dog and left his home in Duarte, nestled in scenic foothills east of Los Angeles that were left bare by wildfires last June. Recent rain sent rocks down steep streets where homeowners built protective barriers out of lumber and sandbags.

"We're packing and leaving because the muds are coming, the mudslides," he told Los Angeles news station KCAL-TV, adding that the risk "comes with the territory living up here."

In northern Los Angeles County, about 120 residents near burn areas of Santa Clarita were ordered to leave late Saturday. During Friday's storm, raging floodwaters overflowed a creek and sent a sheriff's cruiser floating down a street.

Residents who ignore orders to leave can put first-responders at risk later if rescues are needed, said Mike Eliason with the fire department in Santa Barbara County, where canyon areas wiped clean by wildfires were under caution of flash flooding.

Farther north, strong thunderstorms packing heavy rain and possible hail were expected to hit the San Francisco Bay Area. Wine country communities that already experienced destructive flooding this month faced new flood warnings.

"We're seeing mudslides Bay Area wide," said weather service meteorologist Steve Anderson, adding that heavy rain over the past few weeks has saturated the ground.

Wind gusts topping 50 mph brought down trees across Northern California.

In Mendocino County, a massive oak toppled onto an apartment in the city of Ukiah early Saturday, crushing the building and killing a woman as she lay in her bed, fire officials told the Press Democrat newspaper of Santa Rosa. The woman's boyfriend and a 3-year-old boy escaped.

Capt. Pete Bushby of the Ukiah Valley Fire Authority said heavy rain apparently had destabilized the 125-foot tree.

Officials warned of a "high avalanche danger" at all elevations of the Sierra Nevada mountains because of heavy snowfall that has closed several ski resorts. The Sierra Avalanche Center advised Sunday against travel in the area, warning of intense snowfall rates and gale force winds.

Along the coast, big surf rolled ashore, with record 34-foot swells recorded Saturday in Monterey Bay. .

The San Francisco Bay Area was under a high surf advisory along the coast until early Tuesday with waves of up to 19 feet expected, National Weather Service meteorologist Steve Anderson said.

"Surf will be coming up and down, but coming so fast there's no break," he said.

A historic WWI-era ship called the S.S. Palo Alto and docked near Santa Cruz was torn apart by massive waves Saturday.

Two women were swept from the shore in San Diego, where waves topped 10 feet Saturday. One woman was rescued immediately, but it took lifeguards about 40 minutes to pull the other one from the surf. She was hospitalized in critical condition, San Diego Fire-Rescue Capt. Joe Amador said.