Fifty investigators are looking into a fire at a Canadian military base.

The fire killed four soldiers and hurt 39 others.

Prime Minister Mark Carney said this on Monday.

People are asking why training went on.

Officials knew a fire was burning nearby.

Carney told Parliament in Ottawa that the Canadian Forces National Investigation Service is leading the investigation.

The Royal Canadian Mounted Police are helping.

The fire happened on Saturday.

It was at Canadian Forces Base Wainwright in Alberta.

Carney said a fire was burning in the training area.

Then strong winds pushed it almost a kilometer in less than a minute.

It moved toward soldiers who were gathered there.

He said investigators do not yet know what started the grass fire.

Later he told reporters the government would get answers.

It would do this as quickly and openly as needed.

The fire caught soldiers from the 3rd Battalion, Princess Patricia's Canadian Light Infantry.

Army reservists were also doing live-fire training there.

Nineteen of the injured were in critical condition as of Monday.

Opposition leader Pierre Poilievre represents Wainwright in Parliament.

He said many had severe burns.

They will need weeks or months of intensive care.

Maj. Gen. Wade Rutland said on Sunday that officials knew about the fire for hours.

But they believed it was contained, so training went on.

Then the winds suddenly changed.

About 84 soldiers from Charlie Company were training at two places.

The fire swept into the second place.

Carney said the soldiers were getting ready for a mission next spring.

The mission is to support Canadian troops with NATO in Latvia.

The military named the dead.

They are Sgt. Morgan Wong of Edmonton; Pvt. Shaun Farrell of Prince Albert, Saskatchewan; Pvt. Aidan Goulding of North Vancouver, British Columbia; and Pvt. Hayden Lykkemark of Langley, British Columbia.

On Sunday, Carney ordered flags to be lowered to half-staff.

This was on all federal buildings across the country.

Military liaison officers are helping families at hospitals in Edmonton, Calgary, Red Deer and Wainwright.

Mental health teams and chaplains are supporting soldiers and their families.