A forestry pilot noticed a large area of swamp land on fire just before noon Sunday, and alerted fire crews.
More than 30 firefighters responded from Greenbush, Passadumkeag, Milford, and Bradley.
The flames burned more than three acres of land off the Military Road, just north of Olamon Stream.
It took the crews more than six hours to put out the fire. They had to deal with fairly high temperatures while hauling equipment into a remote area.
Authorities think that a lightning strike may have caused the fire, but at this point are unsure.