CHICO, Calif. (Reuters) - Hundreds of volunteers and police officers spent the Thanksgiving holiday combing through the wreckage of California’s deadliest wildfire, searching for the remains of victims killed in the blaze as rains looked set to complicate their work.

The Camp Fire killed at least 83 people and 563 are still unaccounted for in and around Paradise, a community of nearly 27,000 people that was largely incinerated when the flames swept through two weeks ago, according to authorities.

“We haven’t taken the day off,” Butte County Sheriff Kory Honea said in a video message posted online on Thanksgiving. Some 820 searchers were in the field, he said, sifting ash and rubble for human remains.

“This has been a tough situation for all of us,” Honea said.

Searchers in and around Paradise, 175 miles (280 km) northeast of San Francisco, were expecting heavy rains late on Thursday that could hinder their efforts. Between 4-6 inches (10-15 cm) of rain were forecast to fall by the weekend.

The rains raise the risk of mudslides in areas where the wildfire stripped hillsides of vegetation that would typically hold down the earth.

After rains helped douse the Camp Fire in recent days, about 900 firefighters were holding the blaze in check, said Scott McLean, a California Department of Forestry and Fire Protection spokesman. The fire is now 90-percent contained.

Slideshow ( 7 images )

“It’s wet and muddy, that’s the issue on the fire line,” McLean said.

Warehouses were opened in Chico, a city a few miles (km) west of Paradise, to provide shelter from the cold and rain to residents who lost their homes. Celebrity chef Jose Andres and other culinary professionals cooked hundreds of Thanksgiving meals for evacuees.

Firefighters taking a break from the battle against the remnants of the blaze also helped serve Thanksgiving meals.

“Today you see how the best of America is showing up,” Andres said on CNN, standing in front of tables for evacuees. “Every man and woman here, they are heroes in their own way because they all go away from their comfort zones to do something for their fellow citizens.”

‘HAVEN’T LOST MY HEART’

The cooking and serving of Thanksgiving meals was led by World Central Kitchen, a charity group founded by Andres.

Slideshow ( 7 images )

By the end of the day, the team expected to have served 10,000 to 15,000 meals to people at several locations in the area including Red Cross shelters, said Sam Chapple-Sokol, a spokesman for the effort. Among the celebrity chefs on hand was television personality Guy Fieri, he said.

Katya Phillips, 33, and her family lost their home in Paradise, but she was among the volunteers on Thursday feeding evacuees at California State University in Chico.

“Not only did I lose my house, I did also lose my car, but I haven’t lost my heart so I’m here helping others,” Phillips said by telephone.

The cause of the Camp Fire, which destroyed more than 13,500 homes, remains under investigation.

The state is undertaking the largest single wildfire cleanup operation in its history to remove toxic and radioactive ash and debris at burned home sites, officials said.

A separate California wildfire - the Woolsey Fire, which killed three people and threatened the wealthy beachfront enclave of Malibu near Los Angeles - was declared 100-percent contained on Wednesday.

The rains in northern California, which in some areas were likely to be accompanied by winds of up to 45 miles per hour (72 kph), raised risks of ravines turning into rivers of mud. The Camp Fire has burned across 153,336 acres (62,000 hectares) of the Sierra foothills.

The death toll has been gradually rising, with two more names added to the list on Wednesday to bring the total to 83 people, with 58 of them tentatively identified, authorities said.

The number of people unaccounted for, which has fluctuated widely over the past week, declined to 563 on Wednesday, falling by more than 300 names.

Asked about the effects of rain on the search for remains, Honea said it would make going through debris more difficult but he was less concerned about remains washing away than the headaches posed by mud.

Still, he said some remains might never be found.

“What we’re looking for in many respects are very small bone fragments so, as we go forward, it’s certainly possible that not all of them will be located,” Honea said.