Small human-caused grass fire in Yellowstone

Investigators are looking into who started a small grass fire that temporarily closed the North Entrance to Yellowstone National Park over the weekend.

The fire occurred about 6 p.m. Friday and was quickly contained by firefighters. It burned just four acres of grass and sage between the North Entrance and the Gardiner River.

However, the North Entrance Road was closed for about 90 minutes until the fire was contained.

The National Park Service is asking for help from anyone who was in the area on Friday evening and has information about people using the picnic area near the entrance station.