A wildfire burning northwest of Los Angeles on Sunday has forced the evacuation of over 1,000 people from a popular outdoor recreation area and burned over 12,000 acres, authorities said.

Some 400 firefighters armed with 70 firetrucks and two bulldozers are battling the Post fire, which is just 2% contained, according to Cal Fire. It is burning south of Gorman, California, about 60 miles (96.5 km) northwest of Los Angeles.

The fire, which started Saturday afternoon, is moving to the southeast, toward Pyramid Lake, Cal Fire said. Some 1,200 people have been evacuated from the Hungry Valley recreation area, which has trails for motorcycles and off-road vehicles, since the fire broke out. Two structures have been destroyed so far.

Cal Fire said that efforts to contain the wildfire are being hampered by high temperatures, low humidity and strong winds, forecast to continue through Sunday night.

Water-dropping aircraft are working to halt forward progress of the fire, while firefighters are constructing perimeter fire lines in an effort to get the blaze under more control.