California wildfire threatens thousands of homes outside Yosemite National Park

Flames from a backfire burn as CalFire crews battle the wildfires near Mariposa, Calif. (AP)

A stubborn wildfire burning in the rugged mountains outside Yosemite National Park destroyed at least eight structures Wednesday, and forced thousands to flee their homes.

The California Department of Forestry and Fire Protection said the blaze, known as the Detwiler Fire, nearly doubled in size overnight in Mariposa County and has now scorched roughly 71 square miles.

Merced and Mariposa County Sheriff's Office members attend a wildfire briefing. (AP)

The blaze is only seven percent contained, fire officials said.

The fire is burning near Highway 49, a historical route winding its way up the California foothills of the western Sierra Nevada and dotted with communities and landmarks that sprouted up during the state's Gold Rush. Yosemite National Park remains open, but several roads frequented by tourists were closed.

More than 2,000 people in the town of Mariposa, located outside the park boundaries, are under evacuation orders as the fire burns in steep terrain with dense vegetation.

"I've been here since 1974 and I've never seen Mariposa evacuated," resident Rocky Shaver told FOX 26 News.

Reinforcements are being called in to help get the fire under control, bringing the number of firefighters working to more than 2,200, according to FOX 26 News.

A firefighter sprays water on a back fire while battling the wildfires near Mariposa. (AP)

The fire is also threatening powerlines that provide electricity to the park.

Flames from a backfire burn above fire trucks as CalFire crews battle the wildfires near Mariposa. (AP)

"The safety of our customers and fire fighters responding to the Detwiler fire is our top priority," a Pacific Gas and Electric Company spokesperson said in a statement. "To assist with firefighting efforts we have de-energized several power lines in the fire area at the request of Cal Fire, many power lines have been de-energized to make it safer for Firefighters, Law Enforcement, and residents."

Gov. Jerry Brown on Tuesday declared an emergency, bolstering the state's resources to battle the fire that he said has forced thousands of residents to flee -- and is expected to continue burning.

The cause of the blaze remained under investigation, as smoke from the fire drifted more than 150 miles away to Reno.

Read more from FOX 26 News.

The Associated Press contributed to this report.