A California fire fuelled by high winds forced some 25,000 people to flee their homes on Thursday while thousands more were left without power.
Fire crews are tackling a large blaze tearing through the hills near Silverado Canyon, about, 63 miles southeast of Los Angeles.
As of Thursday evening, the fire had chewed through 6,400 acres of land and was only 10 per cent contained, the Orange County Fire Authority (OCFA) said in a statement.
Some 500 firefighters have been deployed in the operation, OCFA added.
Two Forest Service Firefighters were injured and taken to hospital for evaluation and treatment, authorities said.
Officials did not immediately provide any further details on their condition.
California governor Gavin Newsom enforced mandatory evacuation orders in the Modjeska, Silverado and Williams Canyon areas, Foothill Ranch and Portola Hills west of El Toro and north of the 241 Toll Road.
Voluntary evacuation notices were also issued in several other surrounding areas.
The fire, which has been named the Bond Fire – a reference to where it may have started – reportedly ignited on Wednesday and was whipped up by dry Santa Ana winds.
“We’re in December and we now have active wildfires still in our state,” Mr Newsom told a press conference. “These Santa Ana winds have been quite intense.”
Fire managers said they believed a number of homes and other structures had been damaged or destroyed by the blaze.
“I got a text message from my neighbour saying, ‘Are you okay? Your street is on fire,'” said Giovanna Gibson, a 60-year-old resident of Bond Street, Silverado Canyon.
Ms Gibson was at work at the time. But neighbours later told her the blaze ignited when the owners of a home without power tried to start their generator and it exploded.
Several local media reports also say the fire was caused by a resident. Fire officials have not yet said what they believe started it.
Silverado Canyon, miles from southern California’s suburban sprawl up a single winding road, is home to an eclectic mix of residents including artists and ranchers.
Since the start of the year, wildfires have scorched more than 6,500 square miles (17,000 square km) of California land, according to the California Department of Forestry and Fire Protection.
The yearly land area burned in the western United States has grown eight times larger in less than four decades, the US Forest Service Rocky Mountain Research Station said in research published last month.
Additional reporting by Reuters