PARADISE, Calif. (AP) — The search for remains of victims of the devastating Northern California wildfire took on a new urgency Monday as rain in the forecast threatened to complicate those efforts while also bringing relief to firefighters.

Hundreds of crews and volunteers were searching the ash and rubble where homes stood before flames engulfed the Sierra foothills town of Paradise and surrounding communities, killing at least 77 people in the deadliest U.S. wildfire in a century.

The fire has destroyed more than 10,500 homes while burning 234 square miles (606 sq. kilometers). It was 65 percent contained.

The rain expected to arrive Wednesday could cause wet ash to flow down steep inclines in the mountainous region, forecasters said.

Rescue workers wore white coveralls, hard hats and masks as they poked through debris, searching for bone fragments before rain could wash them away or turn loose, dry ash into thick paste.

A team of 10 volunteers accompanied by a cadaver dog went from house to house in the charred landscape. Some went to homes where they had received tips that someone might have died.

They used sticks to move aside debris and focused on vehicles, bathtubs and what was left of mattresses for possible signs of victims.

When no remains were found, they spray-painted a large, orange “0” near the house and moved on.

Robert Panak, a volunteer on a team from Napa County, said he was trying to picture each house before it burned and imagine where people might have taken shelter.

“I just think about the positives, bringing relief to the families, closure,” Panak said.

The search area is huge and the fire burned many places to the ground, creating a landscape unique to many search-and- rescue personnel, said Joe Moses, a commander with the Monterey County Sheriff’s Office, who is helping oversee the effort.

“Here we’re looking for very small parts and pieces, and so we have to be very diligent and systematic,” he said Friday.

Sheriff Kory Honea said it was possible that the exact death toll from the blaze would never be known. He also questioned whether the search for remains could be completed by midweek when the rain is forecast.

“As much as I wish that we could get through all of this before the rains come, I don’t know if that’s possible,” he said.

About 1,000 names remain on a list of people unaccounted for more than a week after the fire began in Butte County about 140 miles (225 kilometers) north of San Francisco.

Authorities don’t believe all those on the list are missing and the number dropped by 300 on Sunday as more people were located or got in touch to say they weren’t missing.

On Sunday afternoon, more than 50 people gathered at a memorial for the victims at First Christian Church in Chico, where a banner on the altar read, “We will rise from the ashes.”

People hugged and shed tears as Pastor Jesse Kearns recited a prayer for firefighters, rescuers and search teams: “We ask for continued strength as they are growing weary right now,” Kearns said.

Paul Stavish, who retired three months ago from a Silicon Valley tech job and moved to Paradise, placed a battery-powered votive candle on the altar as a woman played piano and sang “Amazing Grace.”

Stavish, his wife and three dogs escaped the fire, but their house is gone. He said he was thinking of the dead and mourning for the warm, tight-knit community.

“This is not just a few houses getting burned,” he said. “The whole town is gone.”

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Associated Press journalists Christopher Weber and Brian Melley in Los Angeles contributed to this report.