US emergency crews have shifted their focus to recovering bodies, not hoping to find survivors from a mudslide.
Hopes are fading of finding anyone still alive
Cadaver dogs have been brought to a site east of Los Angeles where five people are still missing.
Eleven bodies have already been recovered from two campsites hit by mudslides triggered by unusually heavy rains on Christmas Day.
Other people managed to escape the torrent of mud as it uprooted trees and rocks and surged into the campgrounds.
More than 20 people were at Saint Sophia Camp, a Greek Orthodox retreat near Waterman Canyon, when the heavy rainfall created a wave of mud 15 feet (4.5 metres) just after 1300 local time (2100 GMT).
A separate landslide hit a campground in nearby Devore where at least two people died and 32 trailers were buried.
The last survivors from the Saint Sophia camp were found within hours of the mud engulfing the caretaker's cabin where families were sharing Christmas lunch.
Three days later, Chip Patterson of the San Bernardino County Sheriff's Department acknowledged that the continuing effort was more likely to find bodies than survivors.
"It's been several days now and, basically, based on the description and what I've seen of the actual devastation and the nature of this disaster, our hopes are certainly not high for finding people alive. But we are still working on that, of course."
The Saint Sophia caretaker, his wife and one of his children are among the missing. Two of his daughters have already been found dead.
The recovery teams are hoping to reach all the victims before the arrival of another storm forecast to hit the area, which could make their work far harder.
The Christmas Day storm covered the area with about 3.5 inches (9 centimetres) of rain - the most severe downpour in the region for 20 years.
The area was previously hit by devastating wildfires in October and November that scorched tens of thousands of acres across southern California.
Experts say that made the canyon more susceptible to mudslides because there were fewer roots to bind the soil to the mountainside.