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 spread across around 50 square kilometers of land, authorities said.

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

The fire, which started on 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.

No homes were threatened by the fire but two commercial buildings have been damaged, the Los Angeles county fire department said on Sunday.

No injuries were reported. The cause was under investigation.

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.

(With input from Reuters, AP)