Thick smoke rises Sunday from the hills above the San Gabriel Mountains in the Angeles National Forest near Los Angeles.
- Wildfire near Los Angles forces evacuation of San Gabriel Canyon
- The area is popular with outdoor enthusiasts
- No buildings are threatened
- Fire-tracking site says cause of blaze is under investigation; report says car fire started it
Los Angeles (CNN) -- California's recreation-rich San Gabriel Canyon will be closed for Labor Day while crews battle a wildfire in steep, bushy terrain.
Authorities evacuated the area Sunday, disrupting the Labor Day holiday weekend plans of thousands of outdoor enthusiasts.
The 3,600-acre Williams Fire broke out Sunday in the Angeles National Forest, an urban recreation area near Los Angeles that's popular with hikers, campers and off-road vehicle owners.
While precise evacuation numbers were unavailable, between 10,000 and 12,000 people use the area during an average holiday weekend, according to Inciweb, the government fire-tracking website.
No buildings are in danger from the fire, which is burning to the northeast toward a wilderness area, Inciweb said.
About 300 firefighters are working on the blaze, according to Inciweb.
Inciweb said the cause of the fire was under investigation. CNN affiliate KTLA-TV in Los Angeles, citing a U.S. Forest Service official, reported the fire began Sunday afternoon when a car caught fire.
The Red Cross has opened an evacuation center in Glendora, California.
