The Garceau Fire burning 10 miles west of Polson has burned 1,500 acres, according to Inciweb.
"This was a very active fire with almost 100% intense heat within the main perimeter," mappers noted. "There was non-forested habitat between the two main polygons in Section 34 which likely had more heat/burn than was visible on the IR scan due to flashy fuels."
The CSKT Division of Fire confirmed Tuesday evening that the wildfire was burning in the Hot Springs area. Officials say the blaze was human-caused.
The fire reportedly started near houses around 2 p.m. Tuesday. Fire behavior is listed as extreme, but it was moving east and away from buildings on Tuesday evening.
The Montana DNRC says more than 80 crew members are on the scene.