GRIDLEY, CALIFORNIA: A Northern California wildfire that destroyed a foothill hamlet has become the state's deadliest blaze of the year with 10 people confirmed dead — and the toll could climb as searchers look for 16 missing people.

The North Complex fire that exploded in wind-driven flames earlier in the week was advancing more slowly Friday after the winds eased and smoke from the blaze shaded the area and lowered the temperature, allowing firefighters to make progress, authorities said.

However, the smoke made for poor visibility and fire helicopters couldn't fly Thursday.

In most parts of the state, red flag warnings of extreme fire danger because of hot, dry weather or gusty winds were lifted.

Only a day or two earlier, the North Complex fire tore through Sierra Nevada foothills so quickly that fire crews were nearly engulfed, locals fled for their lives to a pond, and the town of Berry Creek, population 525, was gutted.

On Thursday, Butte County sheriff's Capt. Derek Bell said seven bodies were discovered, bringing the total to 10 in two days. At least four people with critical burns were hospitalized.

Deputies and detectives were searching for human remains as they made their way into devastated areas with a team of anthropologists from Chico State University, Bell said.

Burned-out and overturned cars, downed power lines and the ruins of buildings littered Berry Creek and nearby areas, the Sacramento Bee reported. One hatchback found on a dirt road had three dead dogs in it, while a pickup truck had the remnants of a guitar case and melted CDs in the bed.

More than 2,000 homes and other buildings had burned in the fire, which began several weeks ago as a lightning-sparked collection of blazes northeast of San Francisco. The final toll is expected to be much higher. Damage assessment teams planned to begin a methodical search of the burned areas on Friday.

Among those unaccounted for were Sandy Butler and her husband, who had called their son to say they were going to try to escape the flames by finding shelter in a pond.

"We're still hoping and praying for good news," said Jessica Fallon, who has two children with the Butler's grandson and considers them her own grandparents. "Everything is replaceable, but not my grandparents' lives. I'd rather lose everything than those two. They kind of held the family together."

Fallon said she'd been peppering hospitals with phone calls in search of her grandparents. There was no word of them late Thursday night.

The speed and ferocity of the fire astonished observers, even those who remembered a blaze only two years earlier that killed some 85 people and devastated the town of Paradise, a few miles away from the current blaze.

Residents jammed the main road out of town on Wednesday amid falling ash and red skies. Authorities lifted an evacuation warning for Paradise on Thursday but authorities urged people to remain alert.

A crew fighting the fire was overrun by flames Wednesday when winds shifted and its members escaped with only minor injuries after deploying emergency shelters. It was the second time in two days that firefighters in California had to take the rare last-ditch effort to save their lives.

The blaze is among 29 major wildfires burning from the Oregon border to just north of Mexico. More than 4,800 square miles (12,500 square kilometres) have burned so far this year — more land than Rhode Island, Delaware and Washington, D.C., combined — and fall is typically the worst season for fires. Nineteen people have been killed and at least 4,000 structures have burned across California.

"It's a historic season on top of a historic season that replaced a historic season. We just keep setting new precedents, and then we keep destroying them," said Sean Norman, a battalion chief with the California Department of Forestry and Fire Protection.

Smoke blew into vineyards in wine country north of San Francisco and rose above scenic Big Sur on the Central Coast and in the foothills and mountains of Los Angeles, San Bernardino and San Diego counties in the southern part of the state.

President Donald Trump spoke with Gov. Gavin Newsom "to express his condolences for the loss of life and reiterate the administration's full support to help those on the front lines of the fires," according to White House spokesman Judd Deere.

Neighbouring Oregon and Washington also have been besieged.

More than 1,400 square miles (3,625 square kilometres) have burned this week in Oregon, where hot, windy conditions continued. Authorities said more than 500,000 people — more than 10% of the state's population — have been forced to evacuate.

Wildfires have scorched nearly 937 square miles (2,426 kilometres) in Washington.