An uncontrolled wildfire in San Bernardino County, California, forced mandatory evacuations Saturday in the mountain communities of Running Springs and Arrowbear Lake, along with other areas.

Five hundred firefighters were using hand lines, hoses and fixed-wing aircraft to fight the Line fire, which started Thursday evening and exploded overnight as temperatures climbed to 110 degrees.

The fire doubled in size early Saturday from 3,800 acres in the city of Highland to 7,122 acres by the evening as it spread northeast toward Running Springs and Arrowbear Lake, with 0% contained. Steep terrain and lack of access impacted the ability of crews to access some areas of the fires, the California Department of Forestry and Fire Protection said in a statement.

The National Weather Service Los Angeles said weather conditions were exacerbating the Line fire into a “dangerous situation.” Outflow winds from pyrocumulonimbus clouds — thunderstorms that form above sources of intense heat, such as wildfires — were pushing the flames around, the weather service said in a post on the social platform X.

“It’s burning out of control,” said David Cruz, spokesman for the San Bernardino National Forest.

Running Springs, a community of about 4,600 residents, is a major gateway to the popular tourist destinations of Lake Arrowhead and Big Bear. About 735 people live in Arrowbear Lake. On Saturday, residents jammed exit routes as they scrambled to comply with mandatory evacuation orders issued by the San Bernardino County Sheriff’s Department. Images from a live video feed posted on social media showed a long line of cars slowing moving down a single mountain lane.

“There’s a giant traffic jam,” Cruz said.

Other areas under evacuation orders, which are issued when conditions are immediately dangerous and life-threatening, include:

—The area from Calle Del Rio to Highway 38, including Greenspot Road North

—All underdeveloped land east of Highway 330 to Summertrail Place and north of Highland Avenue

—The areas of Running Springs east of Highway 330 and south of Highway 18

—The area east of Orchard Road to Cloverhill Drive from Highland Avenue north to the foothills

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