On December 28, 2000, at 0724 hours, fire fighters from a career fire department responded to a structural fire at a local church. A 49-year-old captain (Injured Fire Fighter #1), a 28-year-old fire fighter/engine operator (Injured Fire Fighter #2) assigned to drive an air service truck (Air Service 1), and two 27-year-old fire fighters (Injured Fire Fighters #3 and #4) were injured while performing interior suppression activities when a section of the roof collapsed, trapping them inside the structure. At 0728 hours, the Chief arrived on the scene, assumed incident command (IC), and reported that he had a fire in a large church, which was not heavily involved. The IC radioed a hydrant position and asked central dispatch to tone out a second alarm. At 0730 hours, Fire Fighter #1 pulled a 1¾-inch preconnect off Engine 4 and advanced to the double doors, where he met up with his crew. The IC ordered this crew (the Captain from Engine 4 and Fire Fighters #1 and #2) to enter the structure for an aggressive fire attack; however, the IC instructed them not to enter the structure very far. At 0732 hours, Air Service 1 (a captain and Injured Fire Fighter #2) arrived on the scene and pulled a second 1¾-inch preconnect off Engine 4 and advanced it to the front doors of the structure. At 0734 hours, Engine 5 arrived on the scene with Injured Fire Fighters #1 and #4 and an engine operator. Upon arrival, the IC ordered them to pull a third 1¾-inch preconnect from Engine 4 and advance into the structure. At approximately 0737 hours, the crew from Engine 5 (Injured Fire Fighters #1, #3, and #4) and the crew from Air Service 1 (Captain and Injured Fire Fighter #2) met up in a classroom. They noticed intense fire in the ceiling/truss void area where a small piece of ceiling in the northeast corner of the classroom had fallen. At approximately 0740 hours, as the crew from Truck 1 made their way to the front of the structure, the roof collapsed in the classroom area, trapping and injuring Fire Fighters #1, #2, #3, and #4. They began frantically searching for an exit. Injured Fire Fighter #4 located a section of the wall that felt different from the other walls in the room. He began to bang his helmet, still on his head, against this section of the wall. After approximately six blows, he heard glass break and realized that he had located a window. The Captain from Air Service 1 helped clear the remaining section of the window and assisted Injured Fire Fighters #4, #2, and #3 exit the classroom through the window. Injured Fire Fighter #1 was able to locate the classroom door, and the IC led him out of the classroom, into the hallway, and out of the structure. NIOSH investigators concluded that to minimize the risk of similar occurrences, fire departments should: 1. ensure that the department's standard operating procedures (SOPs) are developed, followed, and refresher training is provided; 2. ensure that fire command always maintains close accountability for all personnel at the fire scene; 3. ensure that incident command conducts an initial size-up of the incident before initiating fire-fighting efforts and continually evaluates the risk versus gain during operations at an incident; 4. ensure that fire fighters use extreme caution when operating on or under a lightweight truss roof and develop standard operating procedures for buildings constructed with lightweight roof trusses; 5. ensure that fire fighters performing fire-fighting operations under or above trusses are evacuated as soon as it is determined that the trusses are exposed to fire; 6. explore using a thermal imaging camera as a part of the exterior size-up; 7. ensure that the assigned rapid intervention team(s) (RIT) complete search-and-rescue operations and are properly trained and equipped; 8. ensure that fire fighters are equipped with a radio that does not bleed over, cause interference, or lose communication under field conditions; 9. ensure consistent use of personal alert safety system (PASS) devices at all incidents and consider providing fire fighters with a PASS integrated into their self-contained breathing apparatus which provides for automatic activation; 10. establish written standard operating procedures, record keeping, and conduct annual evaluations to monitor and evaluate the effectiveness of their overall SCBA respirator maintenance program.