At approximately 7:00 pm, August 10, 2005, two dozer bosses and one contract dozer operator, assigned to Division M, Tarkio Fire, I90 Complex, deployed their fire shelters while in a safety zone during an active period of burning around the safety zone. All three firefighters were unharmed during the event. The Tarkio Fire was one of several fires in the I90 Complex located on the Ninemile Ranger District, Lolo National Forest. Fires in the I90 complex were ignited by human cause along an approximately 20 mile stretch of Interstate 90 west of Missoula, Montana on August 4, 2005. A Northern Rockies Type 1 Incident Management Team assumed command on August 5, 2005. Plans for the day in Division M were to utilize an interagency hotshot crew and dozer to burnout and improve indirect line. A local inversion broke around midday and the fire activity began to increase. At approximately 1600, firefighter resources in Division M were directed to withdraw and move to safety zones. While traveling to the safety zone, the dozer operator and two dozer bosses were alerted by other crews that their primary escape route may be compromised. Following additional communications, the Division Supervisor confirmed to the Dozer Boss that their route had been cut off. The dozer operator and two dozer bosses elected to turn around and return to an alternate safety zone they had previously identified. The alternate safety zone was a combination road junction/switchback. Upon arriving at the alternate safety zone at approximately 1630, they further prepared the area by removing adjacent fuel with the dozer. At approximately 1830, they positioned the dozer in a defensive position near the center of the safety zone with the rear of the dozer facing the direction of the approaching fire. The truck was parked approximately 15 feet in front of the dozer. At approximately 1900, the fire front passed the safety zone. The dozer operator and two dozer bosses crouched in front of the dozer blade initially, and then deployed their fire shelters in the same location to protect themselves from fire embers and heat. By approximately 1910, they were out of their fire shelters, estimating they had actually been in the shelters for approximately two minutes. One of the dozer bosses notified the hotshot crew superintendent that they had deployed their shelters as the fire front passed. The Division Supervisor, Operations Section Chief, Safety Officer, Emergency Medical Technician, and a Sawyer traveled to the site arriving at approximately 2030 to verify that the three individuals were unharmed and to secure the site. The two Dozer Bosses were transported back to the Incident Command Post and the contract dozer operator traveled to his residence for the night. The shelters deployed were all new generation fire shelters. There was no visible damage to the dozer or vehicle.