Firefighters work to contain a wildfire in Mariposa County in central California, the United States, July 25, 2022.(Photo: Xinhua)

 

Photo taken on July 25, 2022 shows vehicles burned in a wildfire in Mariposa County in central California, the United States. (Photo: Xinhua)

 

Photo taken on July 25, 2022 shows vehicles burned in a wildfire in Mariposa County in central California, the United States.(Photo: Xinhua)

 
At least 41 structures have been destroyed by the Oak Fire, now the largest wildfire this year in U.S. western state of California, authorities said Tuesday.

The fast-moving wildfire that began on Friday afternoon near the Yosemite National Park in central California's Mariposa County scorched 18,087 acres (73.2 square km) with 26 percent containment as of Tuesday morning, according to the California Department of Forestry and Fire Protection (Cal Fire).

Around 1,440 structures are still under threat as nearly 3,000 firefighters, with aircraft support, are continuing their efforts against the massive wildfire.

"Fire crews continue providing structure defense, extinguishing hot spots, and building and improving direct fire lines," said Cal Fire in an update.

"Persistent drought, critically dry fuels and tree mortality continue to contribute to the fire's spread. Humidity levels were slightly higher overnight as monsoonal moisture began to move in," the agency added.

The Oak Fire has forced thousands of local residents to evacuate. California Governor Gavin Newsom declared a state of emergency for Mariposa County on Saturday due to the effects of the explosive fire.

Another explosive wildfire, the Washburn Fire, has burned over 4,875 acres (19.7 square km) to date with 87 percent contained after nearly three weeks near the Yosemite National Park. The Washburn Fire has drawn national attention as firefighters are battling the blaze to protect some of the world's oldest and largest trees in the park.

Many of the largest wildfires, including the top five, in California's history have happened in the past few years amid severe drought.

"California continues to experience longer wildfire seasons as a direct result of climate change," said Cal Fire in its 2022 fire season outlook, noting that "continued dry conditions, with above normal temperatures through spring, will leave fuel moisture levels lower than normal, increasing the potential for wildland fire activity."

Wildfires have swallowed over 53,000 acres (214.5 square km) so far this year in the state, according to data released by Cal Fire.