LOS ANGELES (AP) — Richard Harvell's family and friends have joined authorities in searching for the 67-year-old man, following floods that swept through his camping area in California last week.

Harvell was hit by mud and water as he tried to climb into his truck Thursday while a ferocious thunderstorm sent mud, water and debris down a mountainside, inundating roads, homes and vehicles.

Harvell had been camping in the flash-flood zone at the foot of the Tehachapi mountains with a boyhood friend who watched helplessly as he was washed away, his daughter Susan Garcia said Monday.

Family and friends have been searching with a Kern County Sheriff's Department rescue team in looking for him, their efforts sometimes interrupted by bad weather, Garcia said.

The team was using cadaver dogs, Garcia said, but added that she and her five siblings and their mother are holding out hope he's alive.

"We're not going to give up hope until they find him one way or another," she said.

Harvell, a Vietnam War veteran, knew how to survive in the rugged desert area near Boron, where he has lived for years, she said.

"He's definitely able to live off the grid if he had to," she said. "If it's possible for someone to survive this it would be him."

Teams searched the foot of the mountains in the open desert near communities hit hard by mudslides. The area, which saw up to 6 feet of muck, is south of State Route 58 in Tehachapi, where Thursday's powerful thunderstorms triggered massive debris flows that trapped more than 100 cars, buses, RVs and big-rig trucks.

On Monday crews hauled away the last of the trapped vehicles, but tons of hardened mud still needs to be removed before traffic starts flowing again, officials said.

Drainage systems also need to be cleared along an 8-mile stretch of the highway about 80 miles north of downtown Los Angeles, said Florene Trainor, a spokeswoman for the California Department of Transportation. Officials hope to reopen the highway by Thursday.

Geologists determined that nearby hillsides were stable, so there were no fears of another mudslide if it starts raining again, Caltrans officials said.

Carrie Bowen, a district director at Caltrans, said the agency is reviewing storm response to see if Caltrans could have done anything better, a standard procedure following major events.

"I don't know that we could have given the volume of mud," Bowen said.

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Associated Press writer Amanda Lee Myers contributed to this report.