A heavy response of firefighters are battling a wildfire that started Saturday evening near a small mountain town in Colorado, according to White River National Forest officials.

Crews on the ground and in the air are fighting to keep the Williams fire near Silverthorne from growing larger, officials said early Sunday.

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The Williams fire is 1-acre as of early Sunday and is burning near Green Mountain Reservoir between Williams Peak and Chokecherry Gulch. Fuels include live spruce and fir and lodgepole pine, officials said.

The heavy response includes two single engine air-tankers, a heavy helicopter and a light helicopter.

Officials said Sunday the heavy response is successful in keeping the Williams fire from growing.

The activity of the fire was “moderate” overnight Saturday as the area had light precipitation. Fire activity is expected to increase as temperatures rise and the wind increases into Sunday afternoon, the forest service said. 

Firefighters from the Arapahoe-Roosevelt and White River national forests plan to make steady progress Sunday by building containment lines around the fire perimeter and continuing the use of a light helicopter.

About 15 firefighters are working the fire Sunday.

Officials say the fire is presumed to be caused by lightning, but the investigation remains active.