The Salmon Challis National Forest expected full containment of the "Ten Mile" fire near Salmon by 6 pm Thursday. It was estimated at 438 acres.
No structures were threatened.
Investigators have determined the fire was human caused, although the exact cause has not been identified.
The fire was not far from U.S. Highway 93 and is about 10 miles south of Salmon in the Ten Mile Canyon area.
Four engines, four military air tankers and three helicopters were working the fire after it broke out Wednesday afternoon.