At least 13 people have been killed in the southern California mudslides caused by a winter storm and the death toll is likely to increase, Santa Barbara County Sheriff Bill Brown told a news conference on Tuesday, Xinhua reported.
"While we hope it will not, we expect that this number will increase as we continue to look for people who are still missing and unaccounted for," Brown said.
Emergency services, using search dogs and helicopters, are still on the site looking for victims, he said.
He did not say how many people could be trapped.
Strong winter storm on Monday hammered southern California on the U.S. West Coast with heavy downpours, triggering deadly mud flows before dawn on Tuesday.