The fast-moving Mustang Complex has caused temporary closures of the Salmon River Road in Idaho. The forest fire is south of Montana-Idaho border in the Salmon-Challis National Forest, south of the Bitterroot Valley.

The fire grew to over 36,000 acres by Tuesday morning, and firefighters worked late Monday night to protect homes with a planned "burnout" on the southern edge of the forest fire.

The burnout was started ahead of the main blaze to rob the Mustang Fire of fuel and stop the advance to homes and businesses between Cove Creek and the Stoddard Trailhead. The burnout was successful and the fire did not cross the Salmon River Road at that point. Rocks and trees fell onto the road, causing its closure to all traffic Monday night.

The Horse Butte and the East Butte fires merged with the Mustang this week. The fire has also been moving north toward the boundary with the Bitterroot National Forest, and fire officials are watching the advance.