Initial response: Engines 11, 21 and Tower Ladder 15 from City of Groton FD. Upon arrival with heavy smoke from the basement, a "Box Plus" assignment was transmitted with one engine from Poquonnock Bridge FD, one engine from Electric Boat FD, unit from Sub Base FD (FAST), Groton Ambulance, Lawrence and Memorial Hospital Paramedic, City of Groton PD.