POLLOCK PINES: California's wildfire crisis escalated on Tuesday as resurgent strong winds fanned the state's biggest conflagration, drove flames from a separate, smaller blaze into a rural mountain community and prompted widespread precautionary power shutoffs.

Already the second-largest California wildfire on record, the Dixie fire raging since mid-July in the rugged Sierra Nevada range northeast of San Francisco had charred 604,000 acres of drought-parched timber and brush as of Tuesday morning, according to the California Department of Forestry and Fire Protection (Cal Fire).

That tally was up 34,000 acres from the day before, marking one of the fire's biggest 24-hour growth spurts since its earliest days last month.

Doug Ulibarri, a spokesman for the Dixie incident command, attributed the surge to extreme winds that blew up across much of northern California Monday night. But he said containment lines carved by strike teams around nearly a third of the Dixie's perimeter largely held up overnight, despite enlargement of the fire's overall footprint.

Some 1,200 homes and other structures have been lost to the fire, but another 16,000 buildings were listed as threatened, with evacuation estimates ranging from 12,000 to 28,000 residents.

The Dixie is the biggest by far among scores of fires roaring across the Western United States in a highly incendiary summer that experts see as symptomatic of climate change.

A much smaller blaze emerged Tuesday as one of California's leading wildfire threats this week when high winds pushed flames from the so-called Caldor fire, about 65 miles east of Sacramento, into the El Dorado County mountain hamlet of Grizzly Flats.

Cal Fire said two civilians suffered serious injuries during hasty evacuations of the area early Tuesday and that an unspecified number of structures were seen going up in flames.

The Sacramento Bee reported that property losses in Grizzly Flats, a community of about 1,200 residents, included an elementary school, a church and a post office.

The California Governor's Office of Emergency Services put the overall number of people displaced by the Caldor fire at more than 11,000 as of Tuesday night, with mandatory evacuation orders posted for several communities, including Pollock Pines and Somerset.

The flare-ups of the Dixie and Caldor blazes came as the state's largest utility, Pacific Gas and Electric Company (PG&E), initiated deliberate power shutoffs across northern California to reduce wildfire risks posed by possible wind damage to transmission lines.

The company cited forecasts of sustained winds reaching 40 miles per hour, with higher gusts in foothill and mountain areas, as well as tinder-dry vegetation and low humidity levels.

The precautionary blackouts were expected to disrupt electricity service to 51,000 homes and businesses scattered across 18 counties, PG&E said. The company said it expected winds to abate Wednesday, allowing service to be restored within the following 24 hours.