An explosive wildfire is burning largely unchecked after incinerating hundreds of homes and other buildings throughout rural communities north of California's Napa Valley.
The blazes left at least one person dead and sent tens of thousands fleeing down flame-lined streets.
A second massive blaze, less than 200 miles away, destroyed 135 homes as it spread through the Sierra Nevada. That fire was 30% contained.
Both fires have displaced 23,000 people, said Mark Ghilarducci, director of the Governor's Office of Emergency Services. He said one person died in the wildfire about 20 miles north of the famed Napa Valley, and others are unaccounted for.
The fire exploded in size within hours as it chewed through brush and trees parched from four years of drought, destroying 400 homes, two apartment complexes and 10 businesses since igniting on Saturday, fire service spokeswoman Lynn Valentine said.
Residents fled from Middletown, a town of more than 1,000 residents, dodging smouldering telephone poles, downed power lines and fallen trees as they drove through billowing smoke. Several hundred people spent Sunday night at the Napa County Fairgrounds.
Four helicopter firefighters suffered second-degree burns during the initial attack on the fire. They remain in hospital in stable condition.
State governor Jerry Brown on Sunday declared a state of emergency to free up resources. He had already declared a state of emergency for the separate 111-square-mile wildfire south east of Sacramento that has turned the grassy, tree-studded Sierra Nevada foothills an eerie white.
Mr Ghilarducci said this summer's fires are the most volatile he has seen in 30 years of emergency response work. The main cause behind the fast-spreading fires is dry conditions from the drought.
Firefighters have maintained a precautionary line around Grant Grove, an ancient grove of giant sequoia trees, and set prescribed burns to keep the flames from overrunning it.