Thousands of firefighters battle California wildfire near Yosemite National Park

A destructive wildfire near Yosemite National Park spiraled out of control in a dry forest on Sunday and grew into one of the biggest fires of the year in California, forcing thousands of residents to flee the isolated mountain communities.

Some 2,000 firefighters battled the Oak Fire, along with planes and bulldozers, facing harsh conditions including steep terrain, sweltering temperatures and low humidity, according to the California Department of Forestry and Fire Protection, or Cal Fire .

“It’s still hot today,” Cal Fire spokeswoman Natasha Fouts said Sunday. “And the fuel moisture levels are extremely low.”

Ground crew protected homes as tanker planes dropped retardant on 15-metre flames running along ridges east of the small community of Jerseydale.

Light winds blew embers into tree branches “and because it’s so dry it’s easy for spot fires to get established and that’s what fuels growth,” Fouts said.

Firefighters are heading to Oak Fire near Darrah in Mariposa County on Sunday. (David Swanson/Reuters)

The fire started on Friday southwest of the park near the town of Midpines in Mariposa County. Officials on Saturday described “explosive fire behavior” as flames swept through very dry vegetation caused by the worst drought in decades.

By Sunday, the blaze had consumed more than 56 square kilometers of forest land, without any containment, Cal Fire said. The cause was under investigation.

Evacuations were in place for more than 6,000 people living for several miles in the sparsely populated area of ​​the Sierra Nevada foothills, although a handful of residents defied orders and stayed, said Adrienne Freeman of US Forest. Service.

“We urge people to evacuate when told,” she said. “This fire moves very quickly.”

Lynda Reynolds-Brown and her husband Aubrey were awaiting news of the fate of their home from an elementary school evacuation centre. They fled as ash rained down and fire descended from a hill towards their property.

A burnt-out pickup truck is seen in the Jerseydale community of Mariposa County on Sunday. (Noah Berger/Associated Press)

“It just seemed like it was over our house and it was coming very quickly,” Reynolds-Brown told KCRA-TV.

Governor Gavin Newsom declared a state of emergency for Mariposa County due to the effects of the fire.

The flames destroyed at least 10 residential and commercial structures and damaged five others, Cal Fire said. Assessment teams were traveling to mountain towns to check for additional damage, Fouts said.

A sign warning people of extremely high fire danger is seen as the Oak Fire burns near Jerseydale on Sunday. (Justin Sullivan/Getty Images)

Many roads were closed, including a section of State Route 140 which is one of the main routes into Yosemite.

California has seen increasingly large and deadly wildfires in recent years as climate change has made the West much hotter and drier over the past 30 years. Scientists said weather will continue to be more extreme and wildfires will be more frequent, destructive and unpredictable.

Pacific Gas & Electric said on its website that more than 3,100 area homes and businesses lost power on Sunday and there was no indication when it would be restored. “PG&E is unable to access the affected equipment,” the utility said as flames roared Friday.

The Oak Fire was started as firefighters made progress against an earlier blaze, the Washburn Fire, which burned to the edge of a grove of giant sequoias in the southernmost part of Yosemite National Park. The 19 square kilometer blaze was nearly 80 percent contained after burning for two weeks and moving through the Sierra National Forest.