WAINWRIGHT, Alberta — Four Canadian soldiers died and 39 others were taken to hospital after a fast-moving grass fire swept over an infantry company during a live-fire exercise at Canadian Forces Base Wainwright on Saturday afternoon, in what Prime Minister Mark Carney called one of the worst peacetime tragedies for the military on Canadian soil.

Nineteen of the injured were in critical condition with serious burns as of Sunday afternoon, Alberta Premier Danielle Smith said. The wounded were spread across hospitals in Edmonton, Calgary and Red Deer.

The dead were named on Sunday as Sgt. Morgan Wong of Edmonton, a member of the Loyal Edmonton Regiment, and Pte. Shaun Farrell of Prince Albert, Saskatchewan, Pte. Aidan Goulding of North Vancouver and Pte. Hayden Lykkemark of Langley, British Columbia, all of the 3rd Battalion, Princess Patricia's Canadian Light Infantry, Global News reported.

The toll makes Saturday the deadliest training accident in a generation for an army that has spent the past two years expanding its readiness for NATO deployments. The troops at Wainwright were preparing for a rotation to Latvia in the spring of 2027 and for a global response task force that must be able to deploy within hours.

About 350 soldiers from the battalion, which is based at the Edmonton Garrison, were training at Wainwright, one of the Canadian Armed Forces' busiest bases, about 200 kilometres southeast of Edmonton. The unit caught in the fire was Charlie Company, 84 soldiers, most of whom were throwing hand grenades on a range while 10 others carried out a simulated attack, according to Maj.-Gen. Wade Rutland, commander of the 1st Canadian Division.

Rutland described the exercise as "high-intensity combat training with live munitions". Environment Canada had issued a wind warning for the area that afternoon, with gusts of up to 100 kilometres an hour expected.

A grass fire was burning about one kilometre from the range and was judged to be under control, so training continued, Rutland said. Then the wind shifted and drove the flames onto the soldiers in what he said was 30 to 60 seconds, a speed he described as uncommon for a fire covering that distance.

"They saw no fire and then, there was a fire right on top of them," Rutland said.

The emergency was reported at about 4 p.m. local time, the Canadian Armed Forces said in a statement on Sunday morning. The fire jumped the base fence and threatened rural properties and the town of Wainwright, which has more than 6,600 residents. The Municipal District of Wainwright said around midnight that the fire was being held.

Acute Care Alberta declared a Code Orange, the designation for a mass-casualty event, at several hospitals. Thirty ambulance units, including 22 ground ambulances and eight medevac aircraft, were sent to the base along with a medevac plane from Saskatchewan, and Royal Canadian Air Force search and rescue technicians parachuted in to help, Global News reported. The University of Alberta Hospital, home to Edmonton's burn unit, asked the public to stay away from its emergency department except in the most urgent cases.

Wainwright Mayor Bruce Pugh told Time that he had heard cannon and weapons fire before the incident, which was normal for the base, and then the base went quiet. "This would be the largest mass casualty event that we have seen in this community," he said.

Carney said on Sunday that the families of the four dead had been notified. "What followed was one of the worst tragedies for forces on Canadian soil in peacetime," he said, adding that "our country depends on the women and men of the Canadian Armed Forces".

Defence Minister David McGuinty, who travelled to Edmonton, said: "I cannot recall an incident like this in recent memory." He said the loss "reaches communities in every province". Gen. Jennie Carignan, the chief of the defence staff, said the priority remained "the welfare of our members, their families and their community".

The cause of the fire has not been established. Rutland said the munitions in use included grenade launchers, grenades, small arms and ammunition, and that the ignition "could have been any of that or none of it". Military sources told Global News that a gas line or well might have been hit, but Rutland said he did not believe that was the case and that an initial check found the area's oil and gas infrastructure undamaged. The base covers about 609 square kilometres and has more than 200 active gas wells.

The Department of National Defence said there was no indication of terrorism.

Separate military sources told Global News on Saturday night that at least seven people had died. The forces have confirmed only four deaths and said they would not release further casualty details until next of kin had been notified.

The accident happened on the eve of a provincial vote in which Albertans decide on Monday whether to begin the legal process toward separation from Canada. An advance polling station at the Wainwright Communiplex closed early on Saturday, and voters were redirected to Lloydminster and Vermilion.

Rutland said a full investigation would examine the topography, field conditions and vegetation on the range. Doctors have said the most badly burned soldiers face weeks or months of specialised care.