At 1302hrs Dorchester Central dispatched units for the "Odor of Gas" at 703 Douglas St in the Cambridge 1-2 Box area. Chief 1 arrived on location to find A broken gas line with active leak on side Bravo of the structure and established command. Units (Engine 1-3 & Rescue 1-1) arrived on location and stretched 200' of attack line to the structure while crews contained the leak. Command was terminated at 1336hrs as units were dispatched for a second call in the first due area Box Alarm 1-4. Units (Chief 1, Rescue Engine 1-1 & Engine 1-3) would return to the scene with Chesapeake Utilities to assure mitigation of the situation.