On February 22, 2008, a deputy chief and eight fire fighters were injured during an explosion at a restaurant fire in Colorado. At 1340 hours, dispatch reported visible smoke and flames through the roof of a commercial structure. At 1344 hours, police arrived and began evacuating the restaurant and the adjoining retail store. The restaurant was part of a block-long row of adjoining structures. Over the next 25 minutes, 3 engines, 2 ladder trucks, and 24 fire department members arrived on scene including the injured fire fighters. A crew entered the restaurant with moderate smoke showing toward the rear and no flames visible. The crew backed out and entered the retail store (an adjacent building attached to the restaurant) to check for fire in the ceiling but found only light smoke visible. Another crew attempted to ventilate the retail store with a chainsaw, and when the roof was noticed to be spongy, they moved to the roof of the next building, two buildings down from the restaurant. Interior crews operating in all three buildings had backed out. A crew closed the front doors of the restaurant fearing the oxygen would feed the increasingly greenish-black smoke pushing out of the roof of the restaurant. Fireground personnel noticed the front windows of the restaurant and adjoining retail store were vibrating as flames from the roof of the restaurant intensified. At 1427 hours, the restaurant and two adjoining buildings exploded sending glass, bricks, and wood debris into the street. The crew on the roof located two buildings down from the restaurant, felt the front portion of the flat roof heave up about five feet, sending a fire officer to the ground below and temporarily trapping four other fire fighters; all incurred injuries. In addition, four fire fighters, positioned on the ground within 6 feet of the store fronts, were injured by flying debris. Key contributing factors identified in this investigation included fire growth and smoke buildup in the common attic area of the buildings which pressurized and exploded, unrecognized building characteristics that contributed to the fire and explosion hazards, ineffective ventilation, execution of offensive operation SOPs and inadequate staffing. NIOSH investigators concluded that, to minimize the risk of similar occurrences, fire departments should: 1. ensure ventilation techniques are established and executed; 2. conduct pre-incident planning and inspections of buildings within their jurisdictions to facilitate development of safe fireground strategies and tactics; 3. ensure that standard operating procedures (SOPs) for offensive operations are followed, such as, cutting utilities and checking extension into void spaces; 4. ensure that standard operating procedures (SOPs) for a 360-degree size-up are followed; 5. ensure that staffing levels are sufficient to accomplish critical tasks; 6. ensure that the incident commander has sufficient aides on the fireground and has a visual view of the fire building; 7. ensure thermal imaging cameras are used to locate the seat of the fire and monitor fire growth. Although there is no evidence that the following recommendations would have prevented these injuries, they are being provided as a reminder of a good safety practice; 1. ensure that radios are operable in the fireground environment; 2. ensure an adequate water supply is established; 3. ensure that any offensive attack on a commercial structure is conducted using at least a 2½ hoseline; 4. ensure that collapse zones are established when dealing with older commercial structures and worsening fire conditions; 5. train on the specific hazards of fighting fires in modified structures to include ingress/egress points, flashover, and structural collapse; 6. ensure training requirements are standardized across combination department personnel. In addition, municipalities should: 1. establish and enforce building and inspection codes; 2. identify/mark buildings on the C-side (rear) when buildings share common walls or are in very close proximity to each other to aid fire fighters in identifying the fire structure.