Assisted by calmer winds at their backs, firefighters in northern California have tightened their grip on a deadly blaze raging for more than a week around the city of Redding, as 16 people listed as missing turned up safe.

Four others missing from the sprawling fire zone, 260 km north of the state capital Sacramento, remained unaccounted for, said Redding police Sergeant Todd Cogle, who has overseen efforts to find them.

The fire has claimed six confirmed fatalities since gale-force winds whipped the blaze into a flaming cyclone that jumped a river and roared with little warning into Redding and adjacent communities on Thursday night.

Whole neighbourhoods were laid to waste as residents fled for their lives, many with only their pets and few belongings.

Among the dead were two firefighters, as well as two young children who died alongside their great-grandmother as they huddled under a wet blanket while their house went up in smoke.

Also killed was a man who stayed at his home despite an evacuation order.

Authorities said his remains were later found in the rubble of the house, which burned to the ground.

Nearly 1000 dwellings and more than 400 other buildings have been reduced to ruins in a blaze which was started by the mechanical failure of a vehicle.

As of Tuesday afternoon, five days after the Redding fire storm, police were still trying to account for 20 people reported missing by family or friends.

They took the unusual step of publicising the names of the missing, and within hours 16 of them, previously unaware they were being sought, were located when they saw their names on television or the internet and contacted authorities.

Some evacuees have been allowed to return home, though as many as 37,000 remained displaced.

Lighter winds also gave a boost to firefighters battling a pair of additional fires at the southern end of Mendocino National Forest, where 12,200 people were under mandatory evacuation orders.

Those blazes have charred more than 32,000 hectares.

-AAP