The deadly Northern California wildfire that has forced tens of thousands of people to flee their homes burned virtually unchecked on Sunday as fire crews surveyed a small town that was reduced to an ashy moonscape of blackened trees and smouldering rubble.
Firefighters worried that high winds could fan the flames even further.
"Right now, it's going everywhere. We still have a lot of open line," said Anthony Romero, a spokesman for the California Department of Forestry and Fire Protection. "Any event could bring this back up again."
The National Weather Service forecast more hot and dry conditions, with wind gusts expected late in the afternoon.
Keswick, a mountain town of about 450 people, was almost completely wiped out. The San Bernardino County Fire Department was called in to damp down smoking piles of debris that were scattered amid downed electricity lines.
"What we're seeing here is an incomplete burn situation," Captain Doug Miles said as his crew used picks, shovels and rakes to open up piles that just days ago were family homes. The flames laid waste to about 25 blocks, and the "mop up" work was likely to last for days. He said his crew would be looking for anything salvageable, but there was little left standing.
Anna Noland, 49, had to be moved out of areas twice in three days before learning, through video footage, that her house had burned down. She planned to stay at a shelter at Simpson College in Redding while searching for another place to live.
"I think I'm still in shock," Noland said. "It's just unbelievable knowing you don't have a house to go back to."
Mrs Noland was among the 38,000 people who had to leave after the so-called Carr Fire roared into the outskirts of Redding in Shasta County, leaving five people dead — two firefighters, a woman and her two great-grandchildren.
"My babies are dead," Sherry Bledsoe said.
Her two children, 5-year-old James Roberts and 4-year-old Emily Roberts, were stranded with their great-grandmother Melody Bledsoe, 70, when flames swept through the family's rural property on Thursday, on the outskirts of Redding.
A vehicle problem ignited the fire on July 23, but it wasn't until Thursday that the blaze magnified in size and raced into populated areas west of Redding before entering the city limits.
On Saturday, it pushed south-west of Redding, the largest city in the region, toward the small communities of Ono, Igo and Gas Point. The fire grew slightly on Sunday to 360 square kilometres.
It is the largest fire burning in California, threatening more than 5,000 structures. The flames were just 5 per cent contained.
The latest tally showed at least 517 structures destroyed and another 135 damaged, Mr Romero said. A count by Associated Press found at least 300 of those structures were homes.
The firefighters killed in the blaze included Don Ray Smith, 81, of Pollock Pines, a bulldozer operator who was helping to clear vegetation in the path of the wildfire. Redding Fire Inspector Jeremy Stoke was also killed.
Mrs Bledsoe's relatives were among more than a dozen people reported missing after the wind-driven blaze took residents by surprise and levelled several neighborhoods.
Shasta County Sheriff Tom Bosenko said he expects to find several of those people alive and just out of touch with loved ones. Officers have gone to the homes of several people reported missing and have found their cars gone — a strong indication they fled.
Wildfires around the state have forced up to 50,000 people from their homes, said Lynne Tolmachoff, a Cal Fire spokeswoman.
About 12,000 firefighters were battling 17 significant fires Sunday in California, she said.
"We are well ahead of the fire activity we saw last year," she said. "This is just July, so we're not even into the worst part of fire season."
About 160 kilometres south-west of Redding, two blazes that prompted mandatory evacuations in Mendocino County destroyed four homes and threatened more than 4,500 buildings, officials said. They had blackened 101 square kilometres and were 5 per cent contained.
Authorities also issued evacuation orders in Napa County, famous for its wine, where a fire destroyed eight structures. The blaze blackened 150 acres, but was 50 per cent contained on Sunday.
Big fires also continued to burn outside Yosemite National Park and in the San Jacinto Mountains east of Los Angeles near Palm Springs. Those fires burned nearly 260 square kilometres.
Yosemite Valley remained closed to visitors and will not reopen until Friday.