Even the fire-fighting planes couldn't do anything about the flames over the weekend.

With temperatures hovering around 35 degrees, low humidity and unusually dry vegetation, the Oak Fire spread southwest of Yosemite National Park at a rapid rate.

As of Monday morning, the California Forest and Fire Protection Agency (Cal Fire) reported nearly 65 square kilometers of charred terrain -- with zero percent fire containment.

The fire, which broke out on Friday afternoon near the community of Midpines about 70 kilometers from Yosemite, threatened nearly 3,000 buildings.

About 4000 people had to flee from the flames.

A few hundred people spent the weekend in an emergency shelter at Mariposa Elementary School.

The couple Aubrey and Lynda Reynolds-Brown only had a few minutes to get to safety.

"The fire was suddenly above our house and coming down the hill very, very quickly," Lynda Reynolds-Brown told KCRA.

At the emergency shelter, she waited with her husband Aubrey on Sunday for news from emergency services if their home in Lushmeadows in the foothills of the Sierra Nevada could be saved.

While more than 2,000 firefighters used bulldozers to clear the forested hills in the area of ​​the fire to try to stem the spread of the fire by flying sparks, Gov. Gavin Newsom declared a state of emergency for Mariposa County.

By Sunday, about 15 houses had already burned down.

Wind gusts had carried sparks up to a mile away.

In the third year of California's extreme drought, and after years of bark beetle infestations, flames leaped from dead tree to dead tree in an instant.

The dense clouds of smoke also moved over Yosemite National Park.

For the Yosemite Valley region, with Half Dome, El Capitan and the waterfalls Yosemite Falls particularly popular with visitors, the authorities warned of unhealthy air conditions on Sunday.

The national park about 300 kilometers east of San Francisco had already been threatened by the Washburn Fire in the past two weeks.

As the flames spread near the often millennia-old sequoia trees in southern Yosemite, the emergency services had installed sprinkler systems to protect the trees.

Although the fire charred nearly 20 square kilometers of hill country, all of the approximately 500 redwoods (Sequoioideae) of the Mariposa grove were saved, according to the fire department.

By the weekend, the Washburn Fire, the second largest fire of the year in California after the Oak Fire, was about 80 percent contained.

The cause of both fires remained unclear for the time being.

In the north of the state, fires have broken out several times in recent years due to defective power lines or a delayed interruption in the power supply due to unfavorable weather conditions.

A few months ago, the utility Pacific Gas & Electric agreed to pay $55 million in damages to various California counties to avoid criminal prosecution.