Hundreds of firefighters were battling a fast-moving forest fire in northern California on Monday which has killed two people and forced thousands to evacuate their homes.
The McKinney Fire, the largest in the state so far this year, has ravaged 55,493 acres (22,500 hectares) in the Klamath National Forest near the border with Oregon, CalFire said.
The fire was zero percent contained on Monday morning as searing temperatures and gusty winds hampered the efforts of the more than 850 firefighters deployed to combat the inferno.
California and other parts of the western United States have been ravaged by huge wildfires in recent years, driven by years of drought and exacerbated by a warming climate.
The Siskiyou County Sheriff's Office said firefighters found two people dead inside a burned-out car on Sunday in the driveway of a home in the community of Klamath River.
Speaking on ABC News, Sheriff Jeremiah LaRue said firefighters suspected the pair were caught in the swift-moving fire as they tried to flee.
California Governor Gavin Newsom has declared a state of emergency in Siskiyou County, and more than 2,000 residents of the rural area are under evacuation orders.
A heat wave with temperatures of over 100 degrees Fahrenheit (38 degrees Celsius), tinder dry terrain and thunderstorms packing strong winds are complicating the efforts of firefighters battling the blaze.
"Fire growth is expected to spread in all directions," the Klamath National Forest service said in a statement. "Warning for thunderstorms and lightning. Gusty outflow winds of 30 to 50 mph (50 to 80 kph) will be possible near thunderstorm cells."
According to the Siskiyou County Sheriff's Office, the fire has destroyed more than 100 structures -- including homes, a grocery store and a community center -- in the area surrounding Yreka, though it has not yet encroached upon the town of about 7,800 people.
"Surrounding areas should be ready to leave if needed. Please don't hesitate to evacuate," the county sheriff tweeted.
The McKinney fire is California's largest wildfire so far this year -- though it remains much smaller than last year's Dixie Fire, which burned nearly one million acres.
- 'Very, very serious' -
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 be ready to leave, as other fires in recent years had taught them the situation could turn "very, very serious."
Search and rescue teams evacuated 60 people who had been hiking the area's popular Pacific Crest Trail, according to the sheriff's department in Jackson County, Oregon.
CalFire said the cause of the McKinney fire was still under investigation.
The US Forest Service said thick smoke had helped to limit the fire's growth on Sunday, but also meant that firefighters' aircraft were "mostly grounded."
The fast-spreading blaze comes just days after the Oak Fire near Yosemite National Park destroyed dozens of buildings and forced thousands to evacuate.
California, which is facing a punishing drought, still has months of fire season ahead of it.
Other parts of the world have also faced intense wildfires this year, as scientists say climate change is making heatwaves more frequent and more intense, increasing the risk of fires.
In Portugal, a blaze broke out in the Mafra area, north of Lisbon, at the weekend while in France at least four firefighters were seriously injured and motorways were closed.
Also over the weekend, hundreds of firefighters battled a blaze in eastern Germany, with four people injured.