The largest blaze in the US state this year is fuelled by strong winds and extreme drought conditions.
The largest fire in California this year has forced thousands of people to evacuate as it wrecks homes and rips through the western US state’s dry terrain.
The McKinney fire was completely uncontained as it burned in Klamath National Forest in Northern California, the state’s department of forestry and fire protection said on Sunday, consuming more than 21,000 hectares (51,000 acres) near the city of Yreka.
Gavin Newsom, the governor of California, which has already battled several blazes this summer, declared a state of emergency on Saturday, saying the fire had “destroyed homes” and “threatened critical infrastructure” after breaking out on Friday.
The fire was “intensified and spread by dry fuels, extreme drought conditions, high temperatures, winds and lightning storms”, Newsom added in a statement.
More than 2,000 residents were under evacuation orders and some 200 under evacuation warnings, mostly in Siskiyou County, according to the California Office of Emergency Services.
“Surrounding areas should be ready to leave if needed. Please don’t hesitate to evacuate,” the Siskiyou County sheriff tweeted.
Highway 96 and McKinney Creed Road, southwest of the Klamath River, were closed to the public, authorities said.
Yreka resident Larry Castle told the Sacramento Bee newspaper that he and his wife had packed up a few possessions and their three dogs to leave the area for the night.
“You look back at the Paradise fire and the Santa Rosa fire and you realise this stuff is very, very serious,” he said.
Nearly 650 people were working to douse the blaze as of Sunday, the National Wildfire Coordinating Group said.
Firefighting forces were sent from nearby Oregon to help containment efforts, the Oregon State Fire Marshal said, as the Klamath National Forest also deals with the Kelsey Creek Fire.
Fire authorities in California said the cause of the blaze was still “under investigation”.
The US Forest Service (USFS) said “a heavy smoke inversion” had helped limit the growth of the fire on Sunday, but also meant that firefighters’ aircraft were also “mostly grounded”.
Fire crews were working above Fort Jones and west of Yreka “to cut off the fire’s progress”, the USFS said.
The record-breaking blaze was sparked just days after the year’s previous largest fire raged in central California.
The Oak Fire near Yosemite National Park broke out in mid-July and spread rapidly, destroying 41 buildings and forcing thousands to evacuate.
California, which is facing a punishing drought, still has months of fire season ahead of it.
In recent years, California and other parts of the western US have been ravaged by huge and fast-moving wildfires, driven by a warming climate.
Other parts of the world have also faced intense wildfires this year.
On Sunday, both Portugal and France were battling major forest fires, as temperatures rose sharply in Europe over the weekend.