On August 27, 2006, a 43-year-old male career Lieutenant (victim #1) and a 25-year-old male fire fighter (victim #2) died after the floor they were operating on collapsed at a commercial structure fire. At approximately 1230 hours, crews were dispatched to a fire. The victims' engine was dispatched at 1236 hours as an additional unit alarm and arrived on the scene at approximately 1240 hours. At approximately 1251 hours, victim #1, victim #2 and fire fighter #1 advanced a 2 ½-inch hand line through the front of the structure and down an aisle toward the rear of the store. The fire was located in the rear interior of the structure (discount store) that sold a variety of numerous small household commodity items. Approximately three minutes later, the structural members supporting the floor directly below the victims failed. The V-shaped collapse of the floor caused victim #1 and victim #2 to fall into the basement and shelving stocked with merchandise to fall in on top of them. Multiple MAYDAYs were transmitted and the fire fighter assist and search team (FAST) was deployed to the front of the structure where they assisted in the rescue of numerous members who had been operating in the interior of the structure at the time of the collapse. Battalion Chief #1, Lieutenant #1 and fire fighter #1 were freed from the debris. At approximately 1415 hours, victim #1 was removed from the debris in the basement and transported to the hospital. He died the next day as a result of his injuries. At approximately 1435 hours, victim #2 was removed from the basement and transported to the hospital where he was pronounced deceased as a result of his injuries. NIOSH investigators concluded that, to minimize the risk of similar occurrences, fire departments should: 1. consider the possibility of a substandard structure when building information is not available from pre-incident plans; and, 2. consider the live load of water on the structure and go defensive when water load potentially compromises the structural integrity. Additionally, municipalities should: 1. explore means of coordinating information sharing between building and fire departments to increase safety for fire fighters and civilians; and, 2. consider conducting inspections on all commercial structures where a change of occupancy has occurred or renovations are known or suspected, giving special attention to non-sprinklered commercial retail structures.