CHEYENNE, Wyo. (AP) — Firefighters are working to keep a wildfire from reaching Glendo State Park in southeast Wyoming.

The Sawmill Fire has burned about 18 square miles southeast of the park and is 20 percent contained. Some 220 firefighters aided by helicopters and air tankers are battling the fire.

The fire started on Wyoming National Guard training grounds on Saturday and has stayed largely on the Guard land.

State Forester Bill Crapser says the main goal of firefighters is to keep the fire away from Glendo State Park. The east side of the park is closed, but the west side and Glendo Reservoir remain open.

Crapser says so far firefighters have been successful in that goal and are making progress to contain the fire.