Wildfires that prompted the evacuation of homes and campgrounds burned unsubdued early Tuesday after scorching 7,000 acres of Southern California brush and forest land.

No homes were destroyed, authorities said. The cause of both fires remained under investigation.

Three firefighters suffered heat exhaustion Monday as they battled a 5,000-acre blaze on the edge of the San Bernardino National forest west of Palm Springs.

Two campgrounds were evacuated as about 1,000 firefighters, backed by helicopters and planes, worked to contain the fire that began Sunday afternoon.

The blaze was 25 percent contained late Monday night. Temperatures in the Riverside County area were expected to top 100 degrees Tuesday.

In northern Los Angeles County, a 2,100-acre fire in the Lake Hughes (search) area of the Angeles National Forest (search) prompted the voluntary evacuation of a dozen homes. The fire was 20 percent contained late Monday night.

The blaze started about 12:30 p.m. Monday and quickly spread in the heavy brush, fanned by winds that gusted around 20 mph, Los Angeles County fire Inspector John Mancha said.

The fire had moved into thick forest that hasn't burned in 75 years, county Fire Department spokesman Mike McCormick said.

In Alaska, a wildfire near a village of about 60 residents almost tripled in size Monday as warm, dry weather gave new life to it and dozens of other fires in Alaska's Interior.

Officials said conditions were drying out, heating up and taking a turn for the worse following several days of rain.

"The humidity has dropped. The temperature is up, the wind has picked up. Our respite is over," said Gil Knight, of the Alaska Interagency Coordination Center.

The 17,000-acre fire was burning about a mile from the village of Bettles. Fire officials said the blaze, whose cause was unknown, was one of 71 fires already burning statewide.

When the fire started last week, crews built a firebreak to protect Bettles, located about 185 miles northwest of Fairbanks. The village, a tourist draw in the late summer, has about 60 year-round residents.