* Burned acreage increases to 89,194
* Hot weather offers no relief on Sunday
* High winds fan fire's erratic behaviour
The death toll from a Northern California wildfire rose to five with the discovery of human remains believed to be those of a missing elderly woman and her two great-grandchildren, even as fire crews battled on to quell flames that have devastated entire neighbourhoods.
More than 38,000 people remained under evacuation orders on Sunday in and around the city of Redding, about 257 km north of the state capital Sacramento, from a blaze that has destroyed more than 500 buildings and continued to rage largely unchecked into a seventh day.
The Carr Fire, the deadliest and most destructive of nearly 90 wildfires burning from Texas to Oregon, has charred 89,194 acres (36,095 hectares) of drought-parched vegetation since erupting last Monday.
More than 5,012 structures were threatened by the fire, officials said. The flames destroyed 517 structures and damaged 135.
The weather on Sunday is expected to offer no relief for firefighters as it will hit more than 100 Fahrenheit (37.7 Celsius) with low humidity and gusty winds, the National Weather Service said.
An army of some 3,500 firefighting personnel and a squadron of 17 water-dropping helicopters had managed to carve buffer lines around just 5% of the fire's perimeter as of Sunday.
Fire officials say the erratic behaviour of the blaze, stoked by high winds and triple-digit temperatures, has complicated efforts to contain the conflagration.
President Donald Trump on Saturday declared the fire an emergency, authorising federal funds for disaster relief efforts.
At the height of its fury on Thursday night, the fire was whipped into a storm-like frenzy by gale-force winds that drove flames across the Sacramento River into the western end of Redding, as thousands of residents fled for their lives in a chaotic evacuation.
The nearby town of Keswick, with a population of about 450, was reduced to cinders, and two firefighters were killed.
On Saturday, Redding police said they were searching for 17 people still unaccounted for two days afterward.
Shasta County Sheriff Tom Bosenko later confirmed the discovery of three bodies at a fire-ravaged home on the outskirts of Redding.
Bosenko said they had not yet been positively identified but were believed to be remains of three victims identified by relatives in news media reports as 4-year-old James Roberts, his 5-year-old sister Emily and their great-grandmother, Melody Bledsoe, 70.
The Los Angeles Times
reported that Bledsoe's family said she desperately put a wet blanket over the children as their home burned.
The children's mother, Sherry Bledsoe, was quoted by the Sacramento Bee as saying, "My kids are deceased, that's all I can say," as she left the sheriff's office on Saturday.
According to the newspaper's account, Melody Bledsoe's husband, Ed Bledsoe, wept as he recalled trying to get back to the family's house after he had left to run an errand on Thursday, only to learn that the fire was closing in on them.
He told the newspaper that he spoke to the children on the phone as he raced in vain to return in time to save them.
"I talked to them until the fire got them," he was quoted as saying. "I was trying to get to them, I was trying to get to the fire."
So far this year, wildfires have scorched almost 4.3 million acres (1.7 million hectares) across the country, less than last year but still higher than the 3.7 million-acre (1.5 million-hectare) average for the same period over the last decade. California has been particularly hard hit with several fierce blazes menacing large populated areas.
One of those, the Cranston fire, prompted a rare closure of much of Yosemite National Park last week, while another forced mass evacuations from the mountain resort community of Idyllwild, east of Los Angeles.