Polk County wildfire 90% contained The battle appears to finally be winding down in northwest Minnesota. Firefighters there have been battling a historic wildfire in Polk County since Monday. Written By: Matt Henson | × Firefighters with the Minnesota Department of Natural Resources work to put out hot spots along Highway 2 near Mentor. Matt Henson/WDAY According to the Minnesota Incident Command System, the wildfire that burned more than 12,000 acres just outside of Mentor was the largest in the state since 2012 when more than 30,000 acres burned near Warroad. Firefighters spent a fourth day working to put out the fire, which is 90% contained. "A wildfire of this magnitude is pretty rare," said Gregg Knutsen, refuge manager for Glacial Ridge Wildlife Refuge.