On July 21, 2007, a 34-year-old career captain and a 37-year-old engineer (riding in the fire fighter position) died while conducting a primary search for two trapped civilians at a residential structure fire. The two victims were from the first arriving crew at 0150 hours. They made a fast attack and quickly knocked down the visible fire in the living room. They requested vertical ventilation, grabbed a thermal imaging camera, and made re-entry without a handline to search for the two residents known to be inside. Another crew entered without a handline and began a search for the two residents in the kitchen area. A positive pressure ventilation fan was set at the front door to increase visibility for the search teams. The crew found and was removing a civilian from the kitchen area as rollover was observed extending from the hallway into the living room. Additional crews arrived on-the-scene and started to perform various fireground activities before a battalion chief arrived and assumed Incident Command (IC). The IC arrived at 0201 hours and asked the victims' engineer the location of his officer (Victim #2). The officer who assisted removing the civilian from the kitchen briefly re-entered to fight the fire. He then exited and notified the incident commander about his concern for the air supply of both victims who were still in the structure at approximately 0205 hours. Crews conducted a search for the victims and found them in a back bedroom where they had been overcome by a rapid fire event. Key contributing factors identified in this investigation include failure to report the fire by the alarm monitoring company; inadequate staffing; the failure to conduct a size-up and transfer incident command; conducting a search without protection from a hoseline; failure to deploy a back-up hoseline; inadequate ventilation and inadequate training on fire behavior. NIOSH investigators concluded that, to minimize the risk of similar occurrences, fire departments, municipalities, and private alarm companies should: 1.ensure that fire and emergency alarm notification is enhanced to prevent delays in the alarm and response of emergency units; 2. ensure that adequate numbers of staff are available to immediately respond to emergency incidents; 3. ensure that interior search crews are protected by a staffed hose line; 4. ensure that firefighters understand the influence of positive pressure ventilation on fire behavior and can effectively apply ventilation tactics; 5. develop and implement standard operating procedures (S.O.P.'s) regarding the use of backup hose lines to protect the primary attack crew from the hazards of deteriorating fire conditions; 6. develop and implement (S.O.P.'s) to ensure that incident command is properly established, transferred and maintained; 7. ensure that a Rapid Intervention Crew is established to respond to fire fighters in emergency situations; 8. implement joint training on response protocols with mutual aid departments. Additionally standard setting agencies, states, municipalities, and authorities having jurisdiction should consider developing more comprehensive training requirements for fire behavior to be required in NFPA 1001 Standard for Fire Fighter Professional Qualifications and NFPA 1021 Standard for Fire Officer Professional Qualifications and states, municipalities, and authorities having jurisdiction should ensure that fire fighters within their district are trained to these requirements.