LARAMIE, Wyo. (AP) — A wildfire has started in the Snowy Range in southern Wyoming, forcing evacuations of several small communities and backcountry campers.

The fire in the Medicine Bow National Forest began Sunday about 2 miles (3.2 kilometers) north of the Colorado border. The cause of the fire is not known.

There was no immediate information on the number of people evacuated.

The fire crossed Wyoming 230 on Monday, forcing closure of the highway.

Forest Service spokesman Aaron Voos says additional firefighting resources were being requested Monday.

The fire is burning in lodgepole pine and in an area of the forest that sustained heavy beetle kill in recent years. It is estimated to be about 100 acres (40.5 hectares).

The fire was expected to grow because of hot, dry and windy weather conditions.