A Commercial building in New Fairfield was engulfed in flames Sunday night and one person was hospitalized as a result.  Firefighters responded to the structure fire on Sawmill Road around 11pm for an aggressive attack with multiple lines in operation. Mutual aid from Sherman, Putnam Lake and Danbury Fire departments helped with manpower and coverage while New Fairfield firefighters battled what officials said was a very stubborn blaze. Fire units cleared around 3 am to be called back for rekindle. The cause is under investigation.  One person was taken to the hospital for treatment of smoke inhalation. No firefighters were injured.  The building houses an excavation and septic business, a landscaping contractor, and a handmade furniture shop.