A fire that killed four soldiers at a western Canadian military base was sparked by a live grenade exercise, a military official has confirmed.

Brigadier-General Vanessa Hanrahan, commander of the Canadian Forces Military Police Group, told reporters on Thursday that the blaze broke out on a grenade launcher range during military exercises on Saturday at the Wainwright military base in Alberta.

High winds propelled the fire across the base, with conditions rapidly worsening. "A subsequent change in wind direction and velocity significantly increased the fire's intensity," Hanrahan said.

The flames spread to a nearby training area. Because the fire originated in the "permanent danger area" of the range, firefighters were unable to directly combat it, Hanrahan added.

The fire swept through the base on Saturday afternoon during high-intensity combat training involving Charlie Company of the 3rd Battalion, Princess Patricia's Canadian Light Infantry.

At the time, approximately 84 soldiers were split between the grenade range and a second area where they practised attacks on simulated enemy positions. The fire swept into that second training area.

Four soldiers died and 39 were injured, with 27 requiring hospitalisation. The incident is considered one of the worst peacetime tragedies in Canada's military history.

The soldiers and reserve members had been participating in exercises ahead of a planned deployment to Latvia, where Canadian forces maintain their largest international military operation.

The Wainwright base, located in the prairies of Alberta amid wide open grasslands and rolling plains, is one of the largest facilities operated by the Canadian Armed Forces and regularly hosts training exercises involving NATO personnel.