Last night around 6:50pm, Bridgeport ECC received a call about an unknown chemical spill into Island Brook behind 154 Woodbine Cir. Companies traced the source to a basement oil tank at 56 Rogerson Cir. that had broken. Engine 16, Battalion 1, Safety Officer 1, and Engine 15 with the spill van responded to this incident along with the assistance of DEEP. Engine 15 remained on the scene for about 2 hours before being released by DEEP.