Officials said the flames began as a smoldering grass fire roughly a kilometer from the training site several hours earlier, rather than a gas well or pipeline explosion as early unconfirmed accounts suggested. Base administrators had allowed the exercise to continue after judging the initial fire did not pose an excessive risk, before wind gusts up to 100 km/h (62 mph) pushed the blaze across the training grounds and beyond the base perimeter. Authorities reported no signs of terrorism, and Maj. Gen. Wade Rutland, commander of the 1st Canadian Division, said the cause of the fire remains under investigation.
Thirty-nine people remain hospitalized from the fire, including at least 19 in critical condition, according to Alberta Premier Danielle Smith. Prime Minister Mark Carney earlier declared a period of national mourning for what he called one of the worst peacetime tragedies for Canada's military on domestic soil, after the influx of burn patients overwhelmed local medical facilities in Wainwright and prompted a regional airlift and military medical response.