Updated

A powerful storm set off mudslides that blocked major highways and sent rivers and creeks over their banks and into cities across Northern California on Saturday. At least half a dozen people had to be rescued from the rushing water, and forecasters were warning of another storm on Sunday.

California officials urged residents along the Napa and Russian Rivers and on hillsides to collect their valuables, gather emergency supplies and get out.

In the city of Napa, near the heart of wine country, the river was already 5 feet over flood stage. Further inland, Reno, Nev., was seeing its worst flooding since a 1997 flood that caused $1 billion in damage.

Firefighters in the Sonoma area rescued two people from a mobile home park, where 4 feet of rushing water washed at least one home off its foundation, and they were searching for a third person, said Division Chief Bob Norrbom with the Sonoma Valley Fire Authority. Cars floated through the park, pushed by the water.

Elsewhere, television footage showed a stranded driver being plucked from the back of a pickup truck by a rescue helicopter, and another person being pulled to safety through the water.

Rick Diaz went out into a flooded Petaluma neighborhood in a 14-foot Zodiac boat on his own to ferry residents to dry ground and rescue their pets.

"He's a hero," said a tearful Suzi Keber after the wetsuit-clad Diaz rescued two pet lizards from her home.

In downtown San Anselmo, the creek overflowed into as many as 70 businesses, said town administrator Debbie Stutsman. Two people rescued from the rising water there were hospitalized with hypothermia, she said.

"I'm looking out of my office now at merchants bringing their damaged goods out into the street," Stutsman said. "The entire downtown area was under 4 1/2 feet of water."

"It's pretty bad all across town," she said.

Meteorologists had warned that parts of Sonoma, Sacramento, Shasta and Tehama counties were ripe for their worst flooding in years, and they said severe was anticipated upstream in Calistoga, St. Helena and Yountville, as well.

In St. Helena, the Napa River was at record levels, seven feet over flood stage. The last record flood there destroyed dozens of homes and businesses.

Mudslides closed several major roads, including Interstate 80 in the Sierra Nevada about 25 miles west of Reno. Six tractor-trailer rigs were caught up in one slide on the interstate early Saturday, but no injuries were reported.

I-80, the major corridor linking Northern California and points east, was expected to remain closed for at least two days, said California Department of Transportation spokesman Mark Dinger.

"No work can be done until the slide stabilizes and we don't know when that will occur," Dinger said.

The Russian River at the Sonoma County town of Guerneville could rise as high as 11 feet above flood stage after if the storm expected on Sunday hits as expected, officials said.

Together, the two weekend storms could add as much as 6 inches of rain to the already water-logged region, said Rick Canepa, a weather service meteorologist in Monterey. More than 2 feet of snow was forecast in the Sierra Nevada.

One woman suffered a broken leg when a mudslide destroyed her home in Santa Rosa late Friday. It took firefighters nearly an hour to free her from the mud and debris, said Santa Rosa Fire Battalion Chief Andy Pforsich.

Flooding also prompted evacuations of at least five mobile home parks in Nevada's Reno-Carson City area.

Flash flooding and landslides closed Interstate 5 both ways over the Siskiyou Summit near the Oregon line between Hilt and Ashland, Ore., but Oregon officials said three of the four lanes were reopened by midday. U.S. Highway 101 was closed by fallen trees and mud south of Crescent City.

Rain also started moving into Southern California on Saturday, and flash flood watches were issued for large areas burned by the year's wildfires in Santa Barbara, Ventura and Los Angeles counties.

Even Pasadena's Rose Parade was in danger of rain on Monday. The parade has had dry days for half a century, but float builders were still prepared to roll out sheets of clear plastic to protect delicate flowers.

"I'd hate to be selfish to ask God just for this favor, but I came far to help decorate and see the parade for the first time," Jean Steadman, 79, of Georgetown, Texas, she said as she gathered yellow roses for a safari-themed float.