The search for survivors of the deadly mudslides in parts of California's Santa Barbara County continued Sunday even as hopes dwindled to find anyone alive, officials said."We're still in rescue mode and we still hope to find someone alive, although the chances of that are becoming slim," said Justin Cooper, a spokesperson for the multi-agency response team.
The death toll rose to 20 on Sunday with four people still missing, Cooper said.
Another 900 emergency personnel arrived this weekend to join the relief effort conducted by more than 2,100 personnel from local, state and federal agencies, including the U.S. Coast Guard, the U.S. Navy and the American Red Cross.
The ramped-up rescue effort is in response to urgent requests for additional manpower made earlier in the week.
Heavy rains on Tuesday soaked the area near Montecito, north of Los Angeles, where vegetation had been stripped away by the largest wildfire in California's history last month.
Sodden hillsides gave way, unleashing a torrent of mud, water, uprooted trees and boulders onto the valley below and killing people aged 3 to 89.
The destruction covered 30 square miles (78 square km), according to the California Department of Forestry and Fire Protection, and forced the partial closure of one of California's most celebrated coastal roads, the heavily used Highway 101.
Officials ordered residents in most of the southeastern corner of Montecito, which is east of Santa Barbara, to leave their homes for what was likely to be one or two weeks.
Many fled to nearby Carpinteria, where local resident Tessa Nash said they were communicating via a Facebook page called Carpinteria Swap, which is usually focused on buying and selling secondhand goods.
In the last few days, Nash said, it has been carrying information about community-led blood drives and transportation tips.
"We're really joined together," she said. "We're affected here in Carpinteria in the sense that we're taking these people in and a lot of people are out of work because they can't travel. It's a trickle down effect."