Torrential rain fell before dawn on Tuesday after people in Santa Barbara County north of Los Angeles were told to evacuate - some for a second time since December when fire was the threat. But only 10 to 15 percent complied.
Emergency workers using search dogs and helicopters rescued dozens of people from mud-coated rubble in what had been a pristine area between the Pacific and the sprawling Los Padres National Forest.
Communities near Santa Barbara were hardest hit. Mudslides toppled trees, demolished cars and covered blocks of residential neighborhoods with thick mud while blocking Highway 101, a major north-south route.
The death toll was likely to rise from 13, with searchers still picking through damaged and demolished homes for survivors. At one point more than two dozen people were missing, but some were found alive.