Rains Claim 4 Lives; 6 Missing : Downpour: Couple are smothered by mud in their bedroom. A man drowns when Ventura trailer park homes are swept into the sea. The next storm is expected late Friday.

After two days of spectacular drenching, Southern California’s downpour turned deadly Wednesday, claiming at least four lives, leaving six people missing and sending dozens more scrambling for higher ground as rain-swollen rivers carved an unforgiving path through the region’s once dry terrain.

A Ventura County man and his fiance, who was nine months’ pregnant, were smothered when a wall of mud crashed through their bedroom. A few miles away, at least one man was found drowned after the Ventura Beach RV Resort trailer park was inundated. Floodwaters tossed and destroyed motor homes as if they were toys.

Rescue teams safely snatched eight people from the ocean near Oxnard after a U.S. Marine Corps helicopter went down in heavy rains off the coast, but a ninth crew member was still missing late Wednesday. The cause of the crash is under investigation.

Two other people, including a teen-age boy, were feared dead after falling into the raging Los Angeles River in Woodland Hills and in Bell. Another man disappeared in the Santa Ana River in Orange County, apparently trying to elude police who were investigating a drug deal.

On the freeways, a 27-year-old man was killed when his van flipped on a slick Interstate 5 off-ramp in Lebec. In the San Bernardino Mountains, two men described as expert skiers were believed buried by an avalanche on Mt. Baldy Tuesday, but the search was called off Wednesday amid fears of more slides.

Gov. Pete Wilson, saying one of the worst storms in a century had created a situation of “extreme peril,” declared a state of emergency for Los Angeles and Ventura counties. The declaration will pave the way for emergency assistance from the state, as well as federal funds that could provide low-interest loans for those hardest hit.

The governor’s action came at the request of officials in both counties as well as from Los Angeles Mayor Tom Bradley, who said during a press conference: “In my lifetime I don’t ever recall seeing water like this.”

Forecasters say that a lull in the storm today will bring only scattered showers to the Los Angeles area. Residents of the county spent Wednesday laying sandbags, scraping up mudslides and--for thousands of homeless--seeking comfort under metallic silver blankets handed out by local shelters.

But another storm, scooping up tropical moisture generated in the Pacific Ocean, should hit by late Friday or Saturday with the potential for several more inches of rain “to be wrung out . . . and just dumped all over Southern California,” said Marty McKewon of WeatherData Inc., which provides forecasts for The Times.

The brunt of Wednesday’s storm--dropping more than an inch of rain an hour at times--took its toll on the Ventura River, which quickly spilled its banks and submerged the trailer park along U.S. 101.

In an extraordinary sight, dozens of trailers were swept into the river, where some splintered as they passed below a Southern Pacific railroad bridge and others continued into the ocean, where they bobbed eerily under the downpour.

“They looked like Tinker Toys being washed away,” said Arnold Hubbard, owner and developer of the RV park, which serves as a permanent home for about 50 families and provides temporary lodgings to hundreds of campers each year.

“The trailers just started tipping and turning and everything was just a mess,” said Susie Riggs Orm, who fled the park for higher ground.

Ventura County sheriff’s helicopters clattered over small chunks of land that poked above the water, picking up stranded residents and dozens of homeless people who make their camp in a section of normally dry riverbed known as “Hobo Jungle.”

“Hold on, honey!” Scott MacDermott shouted anxiously from the Main Street Bridge as his wife, Marilyn, and two neighbors waited for help on one of the newborn islands in the river. MacDermott, an Oxnard roofer, watched in silence, his hands shaking as he puffed on a cigarette. His tan trailer, tilted by the dark swirling water, was clinging to the ground by a television cable.

“The copters are coming to get you,” he said shortly before the three were airlifted to safety.

Later in the day, county Fire Department divers donned wet suits and hunted for casualties in the muddy water. The body of a 35-year-old man was found, and fire officials said there had been reports of two more bodies, possibly transients, that may have been washed out to sea.

“If the bodies went into the ocean, they tend to sink, and then they float to the surface days later,” department spokesman Barry Simmons said.

Meanwhile, another drama was being played out in the San Fernando Valley, which was still recovering from Monday’s downpour that turned the Sepulveda Dam Recreation Area into an instant lake.

Shortly before noon, 15-year-old Adam Paul Bischoff rode his bike into the swift waters of the Arroyo Calabasas near his home in Woodland Hills and was swept by the 35 m.p.h. current into the Los Angeles River.

Dozens of firefighters, police officers and motorists tried unsuccessfully to respond to his pleas as he hurtled under bridges across the Valley. Rescuers set up a last line of defense at Balboa Boulevard, but before he reached them, the youth disappeared in the brown, debris-filled water and was presumed drowned.

“If that kid could have held on another half mile I think we could have gotten to him,” Assistant Fire Chief Tony Ennis said. Late Wednesday, authorities were searching for the boy’s body.

Some flood victims accepted their predicament with a sense of resignation. In Malibu Lake, a mountainous community five miles south of Agoura Hills, a 12-foot flood threatened dozens of homes, several of which were covered to their eaves by muddy water. Neighbors took to canoes and rowboats to inspect the damage.

“I lost everything in there,” said William Swearinger, as he stood on high ground behind his wood-frame, lakefront home, watching water lapping inside its windows. He did, however, salvage “the important thing--my fishing tackle.”

Not far away, Elmer Carlson noted that a 50-pound container of dried dog food had been spilled open in the bottom of a neighbor’s partially submerged split-level home on South Lakeshore Drive.

“Some ducks swam up and saw the dog food floating and started tapping on the window,” Carlson said. “So we opened it and let them swim in and eat.”

Wednesday’s downtown Los Angeles rainfall of 1.6 inches broke the previous record of 1.3 inches set Feb. 12, 1936, the National Weather Service said. The season total downtown stood at 11.9 inches, compared to just 1.9 inches for the same period last year.

For the first time since the storm started pounding Southern California, it also seemed that wide swaths of the region shared in the havoc:

* Flooding and mudslides closed roads from Pacific Coast Highway in Malibu to the Golden State Freeway in Sun Valley. A collapsed sound wall shut the Ventura Freeway in Calabasas for an hour.

* A two-acre catch basin above the Antelope Valley community of Quartz Hill broke, releasing a wall of water that flooded scores of homes and businesses up to two feet deep.

* Amtrak service between Glendale and Santa Barbara was disrupted for a second day, the Metro Blue Line was halted in Long Beach when mud flooded the tracks and a downpour in the Mojave Desert forced the Discovery space shuttle to scuttle plans for a ride home to Cape Canaveral.

* All 76 miles of the Los Angeles County coastline remained closed, as more sewage spewed into Ballona Creek. Since Monday, more than 38 million gallons of partly treated waste water had been discharged. In South-Central Los Angeles, an underground pipe ruptured, spilling thousands of gallons of sewage into the intersection of 41st Place and Dalton Avenue.

“It was like a volcano spitting water from the manhole,” said resident Woody Woods.

Wednesday’s storm--unlike the week’s earlier downpours--proved both lethal and wet.

In the Ojai Valley community of Foster Park, Glenn Queen, 30, and his fiancee, Michele Bovee, 27, died when a wall of mud crashed through their bedroom. Bovee, who worked in the county tax assessor’s office, was due to have a child in two weeks.

In Bell, witnesses reported seeing someone fall into the Los Angeles River. Fire crews spotted the person briefly, but lost sight of the victim in debris and called off the search.

Rescuers had better luck in Monte Nido, a mountainous community south of Calabasas, where 81-year-old Bernie Thompson was attempting to ford Cold Canyon Creek in his new Oldsmobile. The car stalled and was washed down the stream.

Neighbors Daryl Lev and Randy Davies attempted to reach Thompson by using a long fence plank as a bridge, but the elderly man opened his door and was swept into the river. Thompson’s rescuers plunged into the water but could not reach him. Then Lev, 41, swam to the shore and sprinted 300 feet to another bridge, where he reached down and grabbed Thompson’s arm as he floated past.

Thompson was reported “doing fine,” at a Woodland Hills hospital.

Contributing to this story were Times staff writers Leslie Berger, Richard Lee Colvin, Aaron Curtiss, Richard Holguin, Sherry Joe, Myron Levin, Eric Malnic, Josh Meyer, Bob Pool, Amy Pyle and Ron Russell in Los Angeles. George Skelton reported from Sacramento. Santiago O’Donnell, Joanna M. Miller, Caitlin Rother, Christopher Pummer, Collin Nash and Daryl Kelley reported from Ventura County. John Needham reported from Orange County.