4-01 Box, 12:54 - Engine 43 and Squad 4 were dispatched to 47454 Leonard Calvert Circle in St. Mary's City for the reported building fire. Engine 141 arrived on location and reported they had a fire in a built in utility chase used for passing electrical and plumbing systems between the floors of the historic building. Crews quickly began to open up the bottom floor chase looking for fire extension. Engine 43 and Engine 31 (Bay District) arrived and assisted with water supply and extending a secondary line to the second and third floors. Truck 13 went to the attic area where they located a small fire. The fire was quickly extinguished. Crews worked for an additional 2 hours performing salvage and overhaul. Units picked up and went in service at 15:05. The fire is under investigation by the Maryland State Fire Marshal's Office.