Avalanches of mud carrying entire trees and huge boulders roared down hillsides that were stripped bare by California's worst-ever wildfires two months ago, leaving a trail of death and devastation in their wake.

"We have found a total of six bodies resulting from two separate incidents," said San Bernardino Sheriff's Department spokesman Sergeant Dave Caddel on Friday following the overnight flash-floods and landslides.

The Greek Orthodox youth camp
site was flattened. 

Several of those missing were children aged between six months and 16 years who had been spending Christmas Day in a camping area owned by the Greek Orthodox Church.

"These numbers may fluctuate as time goes on, but we are pretty comfortable with what we found from the survivors," sheriff's spokesman Chip Patterson said.

Misssing caretaker

"They got a one-two punch: fires and now floods... I can't recognise anything down there"

Warren Dorsett,
San Bernardino resident 

Four of the dead had spent Christmas at the Saint Sofia church campground about 100 km east of Los Angeles, while two bodies were found near another campsite eight kilometres away.

Patterson said the group at the Saint Sofia campground had not been taking part in any church-organised activity, and were the guests of the caretaker who was also missing.

"Apparently these people were all family and friends of the caretaker to Saint Sophia Camp, and were all up there for the holidays... and obviously got caught in the flood and the mudslide," he said.

Another 14 people were injured in the overnight landslips, but all except one of the injured were released from hospital following treatment.

Frantic search

Fifty-seven people were rescued from the second campground near a town called Devore late on Thursday after the landslides began.

Dozens of rescuers armed with sniffer dogs were frantically searching for victims and survivors of the latest natural disaster to hit the most populous US state. Fires and a 6.5 magnitude earthquake killed two people in central California last week.

Walls of mud measuring up to 4.5 metres bore down on the campsites and surrounding homes in the mountainous area that was ravaged by flames in October.

"They got a one-two punch: fires and now floods," said resident Warren Dorsett. "I can't recognise anything down there."

The avalanches, laden with huge trees, wreckage and boulders, tore down hillsides, carrying away everything in their paths.

'Impossible' rescue conditions

They filled a canyon, submerged roads and washed away at least two homes.

More than 7.6 centimeters of rain fell on Thursday, creating poor visibility and "impossible" conditions for rescuers overnight, but their task was eased on Friday as the weather cleared.

Firefighters had to negotiate
near impossible conditions

But conditions remained extremely dangerous on the unstable hillsides, with workers negotiating "quicksand conditions" in order to locate victims and survivors.

"Two buildings washed away and we do believe that there were folks in one of the buildings," said San Bernardino Fire Department spokesman Tracey Martinez.

"Folks had no warning. There was a good 15 feet of mud and debris, lots of large trees, a lot of boulders. There is nothing to hold the roots of the trees in, they're just falling over. It was like a flash flood."

Meanwhile, other mudslides and flash floods occurred across southern California on Thursday as the usually-dry region experienced its first rainy Christmas in 20 years.

Emergency service officials had warned that rock and mudslides were extremely likely after rains on mountainous areas where wildfires burned hundreds of thousands of acres and killed four people in October.

Highways across the stricken area were blocked and closed on Friday, as emergency crews prepared to work late into the night in the hope of finding more survivors.