On August 3, 2007, a 19 year-old male fire fighter (victim #1) and a 42 year-old male Captain (victim #2) responding from the same volunteer mutual aid department were fatally injured during a residential structure fire. At 0136 hours, dispatch reported a residential structure fire. While enroute, the fire district's Assistant Chief requested mutual aid from two neighboring departments due to dispatch updating the report to a fully involved structure fire. At 0150 hours, the Assistant Chief (Incident Commander) arrived on scene with four other fire fighters in an engine. At 0151 hours, the first interior attack crew entered the structure with flames visible in the foyer. At 0213 hours, the initial attack crew briefed a new interior attack crew (the victims) from the second mutual aid department on the location of a few hot spots to be knocked down and the presence of light smoke. At 0216 hours, the IC requested ventilation. Horizontal and vertical ventilation was conducted and a powered positive pressure ventilation fan was utilized at the front door but little smoke was pushed out. Minutes later, heavy dark smoke pushed out of the front door. The IC made several attempts to radio the interior attack crew with no response. Approximately 21 minutes after entry, an evacuation horn was sounded. A three member RIT team made entry and located one of the victims, but was unable to fully extricate him. Ultimately, several RIT teams were necessary to recover the victims. At 0237 hours, victim #1 was brought out. At 0248 hours, victim #2 was brought out. Both victims died of smoke inhalation and thermal injuries. NIOSH investigators concluded that, to minimize the risk of similar occurrences, fire departments should: 1. ensure that fire fighters are equipped with a radio, trained on proper radio discipline, and trained on how to initiate emergency traffic when in distress; 2. ensure that the IC conducts a risk-versus-gain analysis prior to committing to interior operations and continues the assessment throughout the operations; 3. ensure that fireground accountability is established via an Incident Command System; 4. ensure that proper ventilation is done to improve interior conditions and is coordinated with the interior attack; 5. ensure that a Rapid Intervention Team is staged and ready to initiate rescue efforts, and that team members have been trained in RIT tactics; 6. ensure that periodic mutual aid training is conducted.