Around 18:00 Norwich Fire was dispatched to the Vacant YMCA on Main St.for white smoke coming from the roof. The PD arrived first and reported heavy smoke from the 2nd floor, and stating a active fire. A short time later Battalion 1, confirmed a working fire. Crews gained entry and laddered the building. SQA reported a active fire on the 2nd floor, The truck company vented the upper floor. With in a short time, the fire was under control, with extensive overhaul. Mohegan tribe was called fast, and Eng 52 and Rescue 5 was added to assignment. Norwich FMO & PD are investigating this incident.