GLENDORA, Calif. -- A wildfire burning in the Angeles National Forest has grown by another 500 acres and fire officials have stepped up the response to fighting the blaze.

U.S. Forest Service spokeswoman Angie Lavell said Monday that an incident management team was set up early in the morning to map out a long-term strategy to contain the 4,000-acre fire and to request additional firefighting resources.

The fire is currently five percent contained and is heading deeper into a wilderness area away from any structures.

Lavell said the Red Cross has set up an evacuation center at the Glendora High School for the visitors and residents at Camp Williams who were evacuated over the weekend to allow for clear passage of fire trucks.

THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.

A wildfire that broke out in the Angeles National Forest has cut short the Labor Day holiday weekend for thousands of visitors who flock to the popular recreational attraction.

The fire broke out near a campground Sunday afternoon and quickly grew to 3,600 acres, or about 5 1/2 square miles. It sent a huge cloud of smoke that could be seen from the coast to the desert inland.

Campgrounds that typically attract up to 12,000 visitors on the holiday weekend, as well as rehabilitation centers and the private community of Camp Williams Resort above the city of Glendora, were evacuated, forest spokeswoman L'Tanga Watson said.

The forest is heavily used by Southern California residents because it is close to populated areas. Fire officials said that while the campgrounds were not in the line of the fire, they had to be emptied so that the only road in and out of the San Gabriel Canyon could be open just for fire trucks and emergency vehicles.

The fire was burning thick brush that was not touched by a destructive fire in 2009, Watson said. She said the flames, fueled by a combination of dry heat and the heavy brush, were marching uphill toward the wilderness.

About 300 firefighters were aided by four water-dropping helicopters and nine air tankers. Fire officials also activated the use of a DC-10 capable of dropping thousands of gallons of retardant.

Firefighters were counting on cooler weather overnight to help them gain control of the blaze, Watson said.

The cause of the fire was under investigation.

The 2009 fire, which killed two firefighters, destroyed 89 homes and blackened 250 square miles of forest, was the largest in Los Angeles County history.

In Northern California, a fire that's been burning since Aug. 18 in a rugged area of Mendocino County has destroyed seven homes and nine outbuildings, fire officials said Sunday. That fire has scorched nearly 64 square miles.

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  • This Sunday, Sept. 2, 2012 photo provided by Mitchell Edwards and taken from a flight leaving Ontario International Airport shows the growing fire in the Angeles National Forest in Southern California. The wildfire has cut short the Labor Day holiday weekend for thousands of visitors who flock to the popular recreational attraction. The fire broke out near a campground Sunday afternoon and quickly grew to 3,600 acres, or about 5½ square miles. It sent a huge cloud of smoke that could be seen from the coast to the desert inland. (AP Photo/Courtesy of Mitchell Edwards)

  • In this Sunday, Sept. 2, 2012 photo, a DC-10 tanker drops fire retardant on a ridge line at fire above East Fork Rd. near Glendora, Calif., in the Angeles National Forest. The wildfire has cut short the Labor Day holiday weekend for thousands of visitors who flock to the popular recreational attraction. The fire broke out near a campground Sunday afternoon and quickly grew to 3,600 acres, or about 5½ square miles. It sent a huge cloud of smoke that could be seen from the coast to the desert inland. (AP Photo/Rick McClure)

  • In this Sunday, Sept. 2, 2012 photo, a firefighting helicopter makes a drop with a water bucket over a fire in the Angeles National Forest near Glendora, Calif. A wildfire that broke out in the Angeles National Forest has cut short the Labor Day holiday weekend for thousands of visitors who flock to the popular recreational attraction. The fire broke out near a campground Sunday afternoon and quickly grew to 3,600 acres, or about 5 1/2 square miles. It sent a huge cloud of smoke that could be seen from the coast to the desert inland. (AP Photo/Rick McClure)

  • A plume of smoke rises from the San Gabriel Canyon area of the Angeles National Forest in the San Gabriel Mountains northeast of Los Angeles on Sunday, Sept, 2, 2012. A wildfire that broke out in the Angeles National Forest on Sunday forced the evacuation of thousands of visitors and sent a huge cloud of smoke that could be seen from throughout the Los Angeles basin. (AP Photo/John Antczak)

  • A firefighting helicopter goes to refill after dropping water on a wildfire in the Angeles National Forest north of Glendora, Calif. Monday, Sept. 3, 2012. A day after the wildfire broke out near a campground and forced the evacuation of thousands of campers and picnickers it had grown to more than 4,100 acres, or roughly 6 square miles, and was just five percent contained. (AP Photo/Jason Redmond)

  • A sign on San Gabriel Canyon Road warns of a street closure as firefighters fight a wildfire in the Angeles National Forest north of Glendora, Calif. Monday, Sept. 3, 2012. A day after the wildfire broke out near a campground and forced the evacuation of thousands of campers and picnickers it had grown to more than 4,100 acres, or roughly 6 square miles, and was just five percent contained. (AP Photo/Jason Redmond)

  • A fire engine pulls away as firefighters fight a wildfire in the Angeles National Forest north of Glendora, Calif. Monday, Sept. 3, 2012. A day after the wildfire broke out near a campground and forced the evacuation of thousands of campers and picnickers it had grown to more than 4,100 acres, or roughly 6 square miles, and was just five percent contained. (AP Photo/Jason Redmond)

  • Firefighters look on as they fight a wildfire in the Angeles National Forest north of Glendora, Calif. Monday, Sept. 3, 2012. A day after the wildfire broke out near a campground and forced the evacuation of thousands of campers and picnickers it had grown to more than 4,100 acres, or roughly 6 square miles, and was just five percent contained. (AP Photo/Jason Redmond)

  • A hand crew looks on from a burnt hillside as firefighters fight a wildfire in the Angeles National Forest north of Glendora, Calif., Monday, Sept. 3, 2012. A day after the wildfire broke out near a campground and forced the evacuation of thousands of campers and picnickers it had grown to more than 4,100 acres, or roughly 6 square miles, and was just five percent contained. (AP Photo/Jason Redmond)

  • A firefighting helicopter drops water on a wildfire in the Angeles National Forest north of Glendora, Calif., Monday, Sept. 3, 2012. A day after the wildfire broke out near a campground and forced the evacuation of thousands of campers and picnickers it had grown to more than 4,100 acres, or roughly 6 square miles, and was just five percent contained. (AP Photo/Jason Redmond)

  • A firefighting helicopter drops water on a wildfire in the Angeles National Forest north of Glendora, Calif. Monday, Sept. 3, 2012. A day after the wildfire broke out near a campground and forced the evacuation of thousands of campers and picnickers it had grown to more than 4,100 acres, or roughly 6 square miles, and was just five percent contained. (AP Photo/Jason Redmond)

  • Members of a ground crew look on as a firefighting helicopter drops water on a wildfire in the Angeles National Forest north of Glendora, Calif. Monday, Sept. 3, 2012. A day after the wildfire broke out near a campground and forced the evacuation of thousands of campers and picnickers it had grown to more than 4,100 acres, or roughly 6 square miles, and was just five percent contained. (AP Photo/Jason Redmond)

  • A sign near homes on San Gabriel Canyon Road in Azuza, Calif. warns of closures as firefighters fight a wildfire in the Angeles National Forest on Monday, Sept. 3, 2012. A day after the wildfire broke out near a campground and forced the evacuation of thousands of campers and picnickers it had grown to more than 4,100 acres, or roughly 6 square miles, and was just five percent contained. (AP Photo/Jason Redmond)

  • A firefighting helicopter drops water on a wildfire in the Angeles National Forest north of Glendora, Calif., Monday, Sept. 3, 2012. A day after the wildfire broke out near a campground and forced the evacuation of thousands of campers and picnickers it had grown to more than 4,100 acres, or roughly 6 square miles, and was just five percent contained. (AP Photo/Jason Redmond)