Rescue crews waded through thick mud in Southern California today to extricate stranded residents and clear roads made impassable by mudslides that have left at least 15 people dead and destroyed around 100 homes.

Two dozen people were missing and 28 people were injured after the mudslides struck Tuesday in an area northwest of Los Angeles that was recently scorched in the state’s largest wildfire on record. Authorities were working to reach 300 people stuck in their homes Wednesday and declared a “public safety exclusion zone,” barring all but emergency crews from the area.

Amber Anderson, a spokeswoman for the joint recovery effort, which involves helicopters, firefighters and emergency workers from several counties, said the affected area was nearly 20,000 acres.

Among those who were reported missing Tuesday were the father of a boy who was swept hundreds of yards downstream, and the father of a sailor stationed in Hawaii.

One of the dead was identified as Roy Rohter, the founder of a Ventura school, who was killed by a mudslide that poured through his home. His wife was rescued and was in stable condition, the school said.

Five highways remained closed Wednesday, including U.S. 101, a main north-south artery, said Tim Weisberg, a spokesman for the California Department of Transportation.

“There are some portions that look like a riverbed,” Weisberg said of the 101. “It’s a mixture of dirt, debris, boulders, rocks. In some areas it can be 6 inches or a foot deep.”

With blue skies overhead Wednesday, officials were working to clear trees, boulders, downed power lines, household items and building material that had been swept onto the roads, said Mike Eliason, a spokesman for the Santa Barbara County Fire Department. Helicopters would continue to attempt rescues for those still holed up in their homes and bulldozers and loaders would be used to clear a path, he said.

“You have huge boulders, 55-gallon drum size or bigger, that tumbled down the hillside and blocked the road,” he said. “Trees snapped, power lines snapped.”

And then there was the mud, congealing on top of it all. Eliason said that he had been waist deep in mud Tuesday and that “once you get in, you can’t get out.”

“It is just a sticky mess that needs to be cleared,” he said. “A little bit of everything you could imagine, including a kitchen sink. Literally, a kitchen sink was found.”

The wreckage of the downpour, coming so soon after the wildfires, was not a coincidence but a direct result of the charred lands, left vulnerable to quickly forming mudslides.

In an interview with CBS on Wednesday, Sheriff Bill Brown of Santa Barbara County said authorities were still working to identify those who could be trapped and isolated in areas that teams have not been able to reach in Montecito and other nearby areas. He said that it was not yet known how many were still trapped.

“I think most people are really shocked at the extent of the damage and how big the impact was to the area,” he said. “Although we knew that this was coming you couldn’t help but be amazed at the intensity of the storm.”

On Tuesday, as the mud rushed into lower-lying neighborhoods in Montecito, a wealthy hillside community where many celebrities have homes, the power went out and gas lines were severed, said Thomas Tighe, a resident. Officials said Tuesday night that it could be several days before gas service would be restored. They also said power failures were affecting more than 6,000 homes and businesses in the area, adding that many parts of Montecito were without drinkable water.