Donald Trump on Saturday blamed "gross mismanagement of forests" for wildfires raging across California that have destroyed an entire town and killed at least nine people.
"There is no reason for these massive, deadly and costly forest fires in California except that forest management is so poor," the US president wrote on Twitter.
He threatened to withhold "billions of dollars" in federal funding unless the problem was addressed.
Officials raised the death toll from five to nine and ordered hundreds of thousands of people to leave areas threatened by the spreading fires on Saturday, with one blaze approaching the city of Malibu, home to Hollywood stars.
The fatalities were reported in a massive late-season inferno in the town of Paradise in Butte County, north of the state capital Sacramento, where about 6,700 structures went up in flames - officially becoming California's most destructive fire on record.
The fast-moving blaze, which authorities have named the Camp Fire, broke out Thursday morning. Fanned by strong winds, it has scorched 36,400 hectares and was only 5 per cent contained late on Friday, the California Fire Department said.
Other large fires raged in southern California, including one just north of Los Angeles and another in Ventura County near Thousand Oaks, where a Marine Corps veteran shot dead 12 people in a country music bar on Wednesday night.
"The magnitude of destruction we have seen is really unbelievable and heartbreaking and our hearts go to everybody who has been affected by this," said Mark Ghilarducci, the director of the California Governor's Office of Emergency Services.
Governor-elect Gavin Newsom declared a state of emergency to provide assistance to the fire-hit areas.
Butte County Sheriff Korey Honea said four bodies were found inside a vehicle in the Paradise area, while another was found nearby. Three more were found outside a residence, and one inside a house. Officials said earlier that five people had died in vehicles caught in the fire.
Dozens of other people were reported missing.
Residents who escaped Paradise posted harrowing videos on social media as they drove through tunnels of swirling smoke and orange flames to outrun the wildfire.
The flames destroyed hundreds of homes, a hospital, a petrol station, several restaurants and numerous vehicles, officials said.
Mandatory evacuation orders were issued for more than 52,000 people in the scenic area in the foothills of the Sierra Nevada mountains.
"The whole lower side of Paradise is totally engulfed in flames right now," Kevin Winstead, a resident of nearby Magalia, told KIEM TV. "All of it is engulfed in flames right now.
"Not one home will be left standing," he said. "I'm devastated."
"We're just hoping that our brand new home that we were hoping to move into tomorrow is not burned to the ground."
California has endured abnormally dry weather for years. Much of the south, including the Los Angeles area, is experiencing drought conditions.
Authorities in southern California said about 200,000 people were under evacuation orders.
The Ventura County Fire Department said the Woolsey Fire had burned about 14,000 hectares and not been contained. Evacuation orders were issued for about 88,000 homes in the county and neighbouring Los Angeles County.
As wind fanned the fires out of control, mandatory evacuation orders were issued for area including the entire city of Malibu. Footage taken from helicopters showed flames racing over hill ridges towards multimillion dollar mansions.
Malibu is one of the most in-demand locations in California for Hollywood stars and has been home to Leonardo DiCaprio, Jack Nicholson, Jennifer Aniston, Halle Berry, Charlize Theron, Brad Pitt and a host of other celebrities.
Reality TV star Kim Kardashian West, who lives just north of coastal Malibu in Calabasas, posted on Instagram that she was forced to flee her home.
"Just landed back home and had 1 hour to pack up & evacuate our home. I pray everyone is safe," she said.
TV star Charlie Sheen tweeted that his father, Martin Sheen, and his mother Janet were both missing - but the pair surfaced unharmed hours later at a beachside evacuation spot.
"We're fine, we're at Zuma Beach and we're probably going to sleep in the car tonight," Martin Sheen told Fox News 11, addressing his adult children.
Sheen said this was the worst fire he had seen in 48 years of living in Malibu.
Director Guillermo del Toro tweeted that Bleak House, his museum of horror movie memorabilia, was also in the path of the flames.