Part of a hillside that towered over the seaside enclave collapsed two days ago after weeks of drenching rain unleashed torrents of mud that buried a four-block area within seconds.

At a hastily called town meeting at an evacuation center, officials warned residents that more slides were likely and that the mud and debris were still moving and unstable.

"We consider that the whole area of La Conchita is unsafe," said Ventura County Deputy Fire Chief Dave Festerling. "We want people out of the area."

Residents and sheriff's deputies wept as the names of the 10 confirmed dead were read out.

But when the names of another 10 people presumed buried were read, four of them stood up in the room to announce that they had survived. This prompted a burst of relieved applause from the 150 or so other residents of the tightly knit town.

Earlier, Ventura County Fire Chief Bob Roper had cautioned that the number of missing was uncertain because members of the bohemian beachfront community came and went without much notice. "Nobody signed a guest book," he said.

Meanwhile, emergency teams used picks, shovels, axes, fiber-optic cameras, sensitive audio equipment, dogs and even their bare hands as they dug down looking for crevices large enough to shelter survivors.

SEARCHERS STILL HOPEFUL

Fire officials vowed to continue until at least Wednesday night before deciding whether the search-and-rescue mission would become a recovery effort for bodies.

Rescuers said they were racing against time as the mound of mud quickly hardened into the consistency of concrete but they still held out hope of finding survivors.

Early in the day, emergency crews recovered the bodies of Michelle Wallet and her three daughters, Hannah, 10, Raven, 6, and two-year-old Paloma.

The four were found on a couch where they had been waiting for husband and father Jimmie Wallet to return from a nearby store with ice cream. The slide flattened their home and drove it about 100 yards (metres) from its foundation.

"They were sitting on a couch together apparently unaware. It appears they never had a chance to get out. The room was flattened," said Scott Hall, head of search and rescue for the Ventura County Fire Department.

As the rescue operation continued, controversy brewed over whether the town would be allowed to remain in the slide-prone area. A retaining wall built after a 1995 mudslide was swept away in Monday's disaster.

Ventura County Supervisor John Flynn said authorities planned to "discuss several policy issues" involving the town's future.

California Governor Arnold Schwarzenegger, who visited the area on Wednesday, threw his support behind rebuilding efforts once the search and rescue operations were completed.

"In the past few days, we have seen the power of nature to cause damage and despair, but we will match that power with our own resolve," he told reporters.

Jack Falk, 48, a longtime La Conchita resident, said the community, located on a slip of land between steep cliffs and the Pacific Ocean, deserved to be saved.