At 0933 hrs. Station 3 was alerted for an outside gas leak at 118 Bullet Run Lane in the 3-9 Box. Engine 32 responded with 4 members. Engine 32 arrived on location and discovered a truck had run over a 500 gallon, in ground gas tank knocking the valve off. Contact was made with a local propane company to respond. Most of the propane was vented prior to arrival.