People in Montecito, a wealthy enclave of about 9,000 people northwest of Los Angeles, had counted themselves lucky last month after the biggest wildfire in California history spared the town.
Santa Barbara County spokesman Amber Anderson said: "We have no idea where they're at".
Rescue efforts are ongoing in Santa Barbara County in California, with search teams looking for people who were caught by massive mudslides that swamped houses and trapped cars on Tuesday.
United States talk show host Ellen DeGeneres and media mogul Oprah Winfrey are among the residents of the community and both have taken to social media to describe what they've seen.
"The house being gone, it's just a house, it's just some clothes and a house", Sam Johnson told Reuters.
Residents in some areas were subject to a new mandatory evacuation on Friday, emergency officials said, adding that the unstable environment remained a threat to residents and emergency responders.
Meanwhile, eight commercial structures were destroyed and 20 commercial structures were damaged, according to the Santa Barbara County Fire Department.
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"Thomas Tighe said he stepped outside his Montecito home in the middle of the night and heard 'a deep rumbling, an ominous sound I knew was. boulders moving as the mud was rising'".
According to some reports, more than 160 people were transported to hospitals for storm-related injuries.
Search and rescue efforts have been slow as crews have to navigate through waist-deep mud, fallen trees, boulders and other debris.
"We're going to help each other out wherever needed", the broadcaster told Ellen DeGeneres on her talk show today.
Power outages are affecting over 6,000 homes and businesses, primarily in the Montecito area.
U.S. Highway 101, the link connecting Ventura and Santa Barbara, looked like a muddy river and was expected to be closed for two days. He says they lived in a voluntary evacuation zone, so they made a decision to ride out Tuesday's storm.
While the storm may be over, the work only now beings for authorities in Santa Barbara County, who are working to find dead, injured and trapped people in the wake of the powerful mud flow, Time reported.
"While some residents cooperated with the evacuations, many did not".