At 2150hrs, Engine 1 w/4 was sent to Doggetts Fork Rd. for a brush fire in the area. Brush 5, Brush 5-1, and Tanker 5 (Frog Level) were close but couldn't locate a brush fire. When approaching the possible scene, Engine 1 stumbled across the commercial fire at a saw mill nearby. All units were diverted and second alarm was requested. This brought Wagon 1, Squad 2 (Ladysmith), Tanker 4 (Sparta), Medic 514, and B-5 returned to the station to pick up Engine 5. The crew from E-1 stretched 3" lines to the sprinkler connection and was able to knock down the bulk of the fire. They later pulled an additional attack line and completed overhaul. W-1 cleared early and was dispatched to a second fire, while the Engine remained onscene for nearly 4 hours.