ANGELES NATIONAL FOREST ( — Crews continued to battle a fast-spreading brush fire Friday in the Angeles National Forest that grew to 2,500 acres by Saturday morning, burning four cabins and forcing the evacuation of at least two firefighters from heat exhaustion. The blaze was 0 percent contained on Saturday morning.

Los Angeles County Fire and Angeles National Forest crews arrived on the scene at Highway 39 near Rincon Red Box Road shortly after 1 p.m. Friday. The fire spread quickly across the dry hillsides under triple-digit heat. By 2:45 the fire had jumped Highway 39 and was continuing to spread up a hillside as a vast smoke plume rose thousands of feet above the fire into the air. Four structures, including three cabins, were engulfed in flames.

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About 400 firefighting personnel have responded to the scene. One helicopter involved in the firefight made an emergency landing alongside a reservoir, possibly after clipping some power lines in the area. Two firefighters were being treated for heat exhaustion. A firefighter was also being treated Friday afternoon for a snake bite. Five firefighters in total have been treated for minor injuries.

Authorities on Friday closed a portion of Highway 39 from Old San Gabriel Canyon Road to the Angeles Crest Highway. Cold Brook, Crystal Lake and Little Jimmy campgrounds were all evacuated.

The South Coast Air Quality Management District also issued a smoke advisory on Friday, warning that air quality will reach unhealthy levels in parts of the mountains and areas downwind of the fire. People in affected areas were being advised to avoid vigorous outdoor activity. People with respiratory or heart disease, children and older adults were being advised to remain indoors.

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On Saturday, firefighting helicopters were patrolling the perimeter of the fire, looking out for flareups and hot-spots.

Investigators were looking into the origin of the fire.

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This is a breaking news report. More information will be provided as it becomes available.

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