SAN BERNARDINO, Calif. (KABC) -- Cooler weather helped crews make progress Friday against a week-old wildfire in a remote area of the San Bernardino Mountains.
Sources say arson is suspected to be the cause of the Lake Fire, which has grown to 30,526 acres and is 20 percent contained.
Higher humidity, clouds and even a few sprinkles allowed firefighters to construct direct lines on the east side of the fire, and also allowed helicopters and air tankers to drop water and retardant on the more active areas of the fire.
Firefighters could make more progress if the higher humidity holds for the next day or two as forecast, said Lee Beyer of the U.S. Forest Service.
"If that develops into thunderstorms, though, that can sometimes cause some pretty erratic winds ... and that could push the fire around again," he said.
The fire erupted June 17 but flared back up Wednesday. During the firefight Wednesday evening, water-dropping aircraft were temporarily stopped because a drone was spotted flying near the fire around 5:30 p.m., Cal Fire officials said.
Forest Service Aviation Officer Mike Eaton said the presence of the drone kept firefighters from delivering 5,000 gallons of fire retardant on the flames and shut down subsequent missions that could have contained a part of the fire.
The cause of the fire is still under investigation, but sources tell Eyewitness News there is a strong suspicion that the cause could be arson.
The Lake Fire, which is burning in the Barton Flats area south of Big Bear near Highway 38, caused around 360 campers at Camp Oakes in the Lake Williams area to be evacuated. The recent flare-ups triggered new mandatory evacuations Wednesday night in the community of Burns Canyon and Rim Rock. San Bernardino County sheriff's deputies also placed the community of Pioneertown under voluntary evacuations.
The Red Cross set up an evacuation center at Big Bear Community Church, 40946 Big Bear Blvd. A second evacuation center has been set up at Copper Mountain College, 6162 Rotary Way, Yucca Valley.
Small animals may be taken to the Yucca Valley Animal Shelter, 4755 Malin Way, Yucca Valley. Large animals may be taken to the Yucca Valley Equestrian Center, 7429 Avalon Avenue, Yucca Valley.
Highway 38 is closed from Angelus Oaks to Lake Williams. Jenks Lake Road and Maple Lane are also closed in Big Bear Lake.
All hiking trails into the San Gorgonio Wilderness and Pacific Crest Trail from Whitewater Preserve to Onyx Summit are closed.
The following campgrounds are closed: Barton Flats, San Gorgonio, South Fork, Skyline, Council, Heart Bar, Oso, Lobo, Heart Bar Equestrian, Wildhorse Equestrian, Coon Creek Cabin, Coon Creek Yellow-post Sites, and Mission Springs PCT Trail Camp.
The Associated Press contributed to this report.
Cooler weather helps crews battling Lake Fire