- 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 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.