US President Donald Trump expressed sadness today after visiting the wreckage of a California town burned to the ground by a devastating wildfire. 

"This is very sad," Mr Trump said after surveying the remains of Paradise, where nearly the only people out on the road were emergency services workers, surrounded by the twisted remains of the incinerated town.

"They're telling me this is not as bad as some areas; some areas are even beyond this, they're just charred," he added after looking at a street lined with melted cars, tree stumps and the foundations of wrecked houses.

Recovery teams with cadaver dogs are pressing on with their search for more victims in the flame-ravaged town as authorities seek clues to the fate of more than 1,000 people reported missing in the deadliest wildfire in state history.

Remains of at least 71 people have been recovered so far in and around the Sierra foothills hamlet of Paradise, which was home to nearly 27,000 residents before the town was largely incinerated by the deadly Camp Fire on the night of 8 November.

More than a week later, firefighters have managed to carve containment lines around 45% of the blaze's perimeter, up from 35% a day earlier, even as the burned landscape grew slightly to 142,000 acres (57,000 hectares).

Besides the toll on human life, property losses from the blaze make it California's most destructive on record, posing a challenge of providing long-term shelter for many thousands of displaced residents.

With more than 12,000 homes and other structures up in smoke, many refugees from the fire have taken up temporary residence with friends and family, while others have pitched tents or were camping out of their vehicles.

More than 1,100 evacuees were being housed in 14 emergency shelters set up in churches, schools and community centres around the region,  an American Red Cross spokeswoman said.

Authorities said more than 47,000 people in all remain under evacuation orders in the region.                  

Search teams, meanwhile, combed through charred, rubble-strewn expanses of burned-out neighborhoods looking for bodies - or anything else that might carry human DNA for identification purposes.

Butte County Sheriff Kory Honea said the latest official roster of people reported unaccounted for by loved ones had grown to 1,011 or nearly 400 more names than were posted Thursday night and more than three times the number counted as missing on Thursday afternoon.

"This is a dynamic list," Mr Honea told reporters at a news conference, explaining that the list was compiled from "raw data" that likely included some duplication of names due to possible spelling errors and multiple sources of information.

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In Pictures: Devastation in Paradise 

But the sheriff said he was determined to release an unrefined version of the list so as not to "let perfection get in the way of progress" authorities hope to make in resolving the fate of those still missing.

Meanwhile, the remains of eight more fire victims were recovered, bringing the death toll to 71, he said.

Some of those still unaccounted for have likely survived but  have not yet notified family or authorities that they are alive, either because they lack telephone service or are unaware anyone is looking for them, authorities said. 

On the other hand, there may be some people who perished but whose relatives have yet to report them missing. Communication disruptions after the fire have added to the confusion.

The disaster already ranks among the deadliest wildfires in the US since the turn of the last century.

Authorities attribute the death toll partly to the speed with which flames raced through the town with little advance warning, driven by howling winds and fueled by drought-desiccated scrub and trees.