While a 5-ton 6X6 former military cargo truck converted for use as a fire engine was making a mobile attack on the fire, the driver, the only person in the vehicle, was operating a nozzle out of his window. The truck was in the green unburned area suppressing the active fire edge when the Low Air Warning System activated and it suddenly came to a stop. The driver was not able to move the vehicle. He got out, looked at the fire, then went back to retrieve his fire shelter. The truck would still pump water and he used a nozzle to wet the area around the immobile vehicle. Another engine, with the Fire Warden and a Fire Chief, came over to help and also sprayed water, but the fire closed in quickly