Weeks after devastating fires tore through Southern California, heavy rains sent mudslides rolling down hillsides in Santa Barbara County on Tuesday, leaving 17 people dead, Santa Barbara's County Sheriff confirmed.
The storm uprooted trees and homes, and left mangled cars and abandoned surfboards on the streets.
Roads turned into debris-filled rivers and swallowed up communities downstream from where the Thomas Fire burned thousands of acres last month.
"It was literally a carpet of mud and debris everywhere, with huge boulders, rocks, down trees, power lines, wrecked cars -- lots of obstacles and challenges for rescue personnel to get to homes," Santa Barbara County Sheriff Bill Brown said.
• Deadly storm: The 17 deaths were reported in Santa Barbara County, authorities said.
• More missing: Officials expect the number to go up as they look for the at least two dozen people who are unaccounted for.
• Hundreds of calls: The storm hit hard around 3 a.m. and until 6 a.m., sheriff's office dispatchers handled more than 600 phone calls for assistance, Brown said.
• Road closed: The 101 Freeway in parts of Montecito and Santa Barbara, will remain closed for at least 48 hours, authorities said Tuesday.
• More rain: By Tuesday, more than 5.5 inches of rain had fallen in parts of Ventura County over two days, the National Weather Service said. In Carpinteria, nearly 1 inch fell in just 15 minutes, the agency said.
'River of mud'
Thomas Tighe told CNN affiliate KCAL he was outside his Montecito home and heard "a deep rumbling, an ominous sound I knew was ... boulders moving as the mud was rising."
He saw two cars moving sideways down the middle of the street "in a river of mud."
Peter Hartmann said the destruction was everywhere.
"There were gas mains that had popped, where you could hear the hissing," he told the affiliate.
"Power lines were down, high-voltage power lines, the large aluminum poles to hold those were snapped in half. Water was flowing out of water mains and sheared-off fire hydrants."
Before the storm hit, Santa Barbara issued mandatory evacuations, including in parts of Carpinteria, Montecito and Goleta, which are below areas scorched by wildfires, county spokeswoman Gina DePinto said.
"While some residents cooperated with the evacuations, many did not. Many chose to stay in place," Brown said.
Sheriff deputies spent Monday conducting door-to-door evacuations for 7,000 people in a mandatory evacuation area.
"Residents are allowed to shelter-in-place in their homes but will not be allowed to move about the area," the Santa Barbara County tweeted.
"Persons failing to abide by the order are subject to arrest for this misdemeanor violation. The Evacuation Order and Warning areas have not otherwise changed."
'Mud came in an instant'
Ben Hyatt said a river of mud crashed through a neighbor's house in Montecito, a community of about 8,000 east of Santa Barbara.
"Apparently, one of their cars ended (up) in their backyard. We have neighbors at (the) top of the street that evacuated to their roof," Hyatt said.
Hyatt said his Montecito house was "surrounded by mud," and a washing machine had drifted into his front yard.
"Mud came in an instant, like a dam breaking. (It) surrounded the house, 2 to 3 feet," he said.
There were several glimmers of hope, as emergency officials rescued stranded residents.
More than 1 inch of rain per hour
The rain fell at more than 1.5 inches per hour in parts of Southern California. About a half inch per hour is enough to start mudslides, said Robbie Monroe of the National Weather Service in Oxnard.
The downpour is overpowering a terrain especially vulnerable in the wake of recent fires.
The Thomas Fire -- the largest wildfire in California's recorded history -- has burned more than 281,000 acres in Santa Barbara and Ventura counties since it began in early December. It was 92% contained, and officials don't expect full containment until later this month.
Montecito and Carpinteria are vulnerable to mudslides because the steep terrain in some places goes from thousands of feet above to sea level to sea level in "a matter of just a few miles," said Tom Fayram, a deputy public works director with Santa Barbara County
"That's definitely at play here. It's just a mess," he said.
Mudslides are not uncommon to the area and can be deadly. In January 2005, a landslide struck La Conchita in Ventura County, killing 10 people.