It may take at least a month for investigators to determine how a grass fire began before suddenly overwhelming Canadian soldiers training in Alberta, reports the CBC. Four soldiers were killed at the base in Wainwright, 19 others are in critical condition, and 20 more have lesser injuries. It appears that the fire had been smoldering for several hours as troops trained with grenades and other munitions in a nearby grassy area. “The fire was 1km (0.6 miles) away when the wind shifted,” said Maj-Gen Wade Rutland, commander of the 1st Canadian Division of the Canadian Armed Forces, per the BBC. “It is not normal for a fire to move a kilometer in 30 to 60 seconds.”
One question already being raised is why the training continued despite the nearby fire, even if it didn’t seem large at the time. “I spoke to my commander last night, and he said within 30 seconds to a minute they saw no fire, and then there was a fire right on top of them,” Rutland said. Still, most of Alberta had been under a strong-wind advisory on Saturday. “If our protocols need to change, then they’ll be updated,” he said. Canadian authorities have ruled out terrorism as a cause of the initial fire, but they remain unsure about how it started. Rutland ticked off the various live-fire exercises underway, adding that it could it have been any or none of them.