At 19:58 hours, Station 15 was dispatched for an Unknown Explosion in the area of the new townhouses under construction in the 199 Block of Clinton Street. The NCC 911 Center received numerous calls of an explosion somewhere on Clinton Street. Rescue 15 under the command of Ladder Captain MacKenzie (15 Captain 2) responded at 20:00 hours and arrived at 20:02 hours assuming Clinton Street Command. Ladder 15-7 responded at 20:02 hours, followed by 15-5 at 20:05 hours and 15-4 at 20:07 hours. Crews from Rescue 15 and 15-7 made access to the structure of origin and the exposure. The structure of origin had the front picture window shattered along with the front door blown open. The rear of the structure had a large opening created by a 100-pound propane tank that exploded entering the structure on the first floor going through the ceiling and finally resting on the 3rd floor. Command requested an FM Unit and representatives from the Collapse Team to respond. FM's 14 & 15 responded along with Chief Harris (13-8) and Collapse Team Leader (Haley - Collapse 2). Command placed the situation under control at 20:13 hours holding units on scene. The structures were unoccupied and there were no injuries. There was no need for any structural stabilization and station 15 units cleared the scene at 22:01 hours turning the scene over to DSFMO. Responding Units: Rescue 15, 15-7, 15-5, 15-4, DSFMO FM-15, FM-15, 13-8, Collapse 2. A total of 22 members responded.