Folks driving along Main Street in Downtown Bangor Sunday may have been alarmed to see a house on fire, but it was actually set by fire crews.The Bangor Fire Department held a training exercise at a vacant apartment building along the waterfront.They set fires throughout the house, then crews had the chance to watch it progress, and practice their attacks.They also simulated searches inside different parts of the home, and practiced doing ventilation.Firefighters say real-life training like this is invaluable. ” ‘Cause you don’t know what’s been built, how the walls are…once the fire gets in the walls, where it’s gonna go. False walls and things like that. this is about the best we can get. As close to real as it gets.”About 60 people turned out to watch the training burn.The apartment building and the building next to it will eventually be razed to make way for a new Tim Horton’s restaurant.