ANGELES NATIONAL FOREST (CBSLA.com) — A brush fire burning near the San Gabriel River has prompted the evacuation of the east Fork community.

The fire reportedly broke out around 2:15 p.m. near the Julius Klein Conservation Camp #19 in the Angeles National Forest, just north of Glendora.

Officials report that the fire was burning uphill and at a rapid rate.

As of 8:30 p.m. Sunday, the blaze — now called the Williams fire — burned at least 3,600 acres.

Officials say the fire is 5 percent contained.

Several crews, including strikes teams and air tankers, are fighting the blaze.

At least 300 firefighters are battling the blaze on the ground.

Officials have reportedly impounded a car as evidence but it is unknown what connection the vehicle has to the blaze. Arson investigators have been out trying to determine if the car was the cause of the blaze.

Firefighters speculated the blaze might have also been sparked by campers who were barbecuing.

Authorities from the scene also report that two people are being treated medically. The first patient is a women suffering from a severe asthma attack. The second patient is reportedly 9-months pregnant and possibly going into labor.

There were reports of a firefighter being injured, not seriously. The firefighter reportedly had suffered from heat exhaustion.

Officials announced late Sunday that San Gabriel Canyon would be closed on Labor Day due to the Williams fire.

Suraya Fadel, reporting from the fire line for CBS2 and KCAL9, said the fact the blaze kept spreading brought an early end to the holiday weekend for more than 1,000 hikers and campers.

She said nearby campgrounds were “closed indefinitely.”

Firefighters had to contend with hot weather and gusty winds as well as dry, rugged terrain.

She reported “there continues to be a fierce aerial fight using a DC-10, as well as state and local aircraft.”

Fadel also reported the flames were heaviest in an uninhabitable part of the canyon.