A fast-moving grass fire that killed at least four soldiers at a western Canadian military base was sparked by an exercise using live grenades, a senior defence official has said.
High winds propelled the blaze across the army base in Wainwright, overwhelming dozens of soldiers.
The incident was one of the worst peacetime tragedies for Canada's military.
"The fire initiated on the automatic grenade launcher range ... [it] initiated as a result of routine military training that was happening on that range at the time," Brigadier-General Vanessa Hanrahan said.
Officials said 27 people remained hospitalised, with several in a critical condition. The soldiers and reserve members were preparing to deploy to Latvia, where Canadian forces have their largest international military operation.
Winds up to 96km/h fed the blaze, but they were below 50km/h leading up to the fire, Major-General Wade Rutland has previously said.
He described the sudden high winds and resulting spread of the fire as an "uncommon, rapid" event in which the flames advanced 1km in 30 to 60 seconds.
"I’ve certainly never seen anything like it," said Major-General Rutland, commander of 1st Canadian Division, which is based in Edmonton, about 210km west of the military site.
A satellite image shows the extent of the blaze. (Reuters: Planet Labs PBC)
Officials identified the dead as Sergeant Morgan Wong, Private Shaun Farrell, Private Aidan Goulding and Private Hayden Lykkemark.
"The nation is in mourning for those brave members of our armed forces whom we have lost," Prime Minister Mark Carney said, adding that he had ordered flags on federal buildings across the country to be lowered to half-staff to honour the victims.
Alberta Premier Danielle Smith said many of the injured would require weeks and months of specialised, intensive medical care.
When the fire began, Major-General Rutland said, 85 soldiers from the 3rd Battalion, Princess Patricia's Canadian Light Infantry, were in "high intensity" combat training using live munitions at the base, which is located in a prairie setting.
Canadian Forces Base Wainwright had 1,310 military and civilian personnel stationed there as of 2021, according to census data.
Wainwright is one of Canada's busiest military training bases, where soldiers prepare for combat operations. (Reuters: Camden Scott/Canadian Forces/File photo)
The base houses the Canadian Manoeuvre Training Centre, which runs training scenarios and exercises for the army.
Mr Carney said those affected in the fire came from military bases across the country.
Military and civilian firefighters fought the fire through the night in "some of the worst conditions imaginable", Mr Carney said.
Twenty-two ground ambulances and eight air ambulances responded to the scene.
Patients are being treated in Edmonton, Wainwright, Calgary and Red Deer.
Military search and rescue technicians also parachuted into the site.
Health staff in Edmonton said a "code orange", or mass-casualty event, was declared to coordinate the medical response for patients being transported from Wainwright.
The town of Wainwright, with a population of about 6,600, is just north of the base.
Reuters