OTTAWA -- On the eve of Alberta’s referendum, Prime Minister Mark Carney and Premier Danielle Smith addressed a tragedy far removed from the province’s political debate. Both offered condolences Sunday after a fire at Canadian Forces Base Wainwright killed four members of the Canadian Armed Forces and sent 39 others to hospital. “The nation is in mourning for those brave members of our armed forces whom we have lost, and I have asked that the flags on all federal buildings be flown at half-mast to honour them,” Carney said. He also offered words for the wounded and expressed solidarity with the families, friends and colleagues of everyone affected. “Canadians come together in crisis. That is the best of our country,” he said. Smith described the tragedy as heartbreaking, extending condolences on behalf of the Alberta government. “I extend my deepest condolences to the families who have lost loved ones and wish for those who have been injured to have a full recovery,” she said. “Our thoughts also go to the military personnel, families, and colleagues facing uncertainty and grief during this incredibly difficult time.” The fire broke out at about 4 p.m. Mountain time Saturday in a training area at CFB Wainwright. Despite efforts to contain the blaze, the flames spread quickly amid strong winds. The four military members killed were identified as Pte. Aidan Goulding of North Vancouver, Pte. Sean Farrell of Prince Albert, Pte. Hayden Leichmark of Langley and Sgt. Morgan Wong of Edmonton. Thirty-nine people were taken to hospital. In the latest update provided, 19 were listed in critical condition, eight were stable and 12 were ambulatory. “This is one of the hardest days that the Canadian Armed Forces has had to face at home in peacetime,” Defence Minister David McGuinty said. “The entire defence team grieves with these families.” The cause of the fire remains under investigation. Despite reports that an oil or gas line may have contributed to the blaze, Maj.-Gen. Wade Rutland said an initial assessment found no indication of damage to oil and gas infrastructure. But officials have not ruled out ordnance or ammunition as the source of the initial spark. A board of inquiry will be convened, though it could take weeks before investigators reach any conclusions. In the meantime, officials are thanking emergency responders for their efforts over the weekend. Smith acknowledged the incident could also take a toll on those who helped in the wake of the fire. “We also understand the strain such incidents can have on our front-line staff,” she said. “Which is why a significant priority for today is connecting with those who were involved in the response and ensuring that they have access to mental health supports.” Carney described those killed and injured as men and women who were training to serve and defend Canada. He pledged that the country would now serve them and their families in the aftermath of the tragedy. “We will be there for their families for as long as they need,” he said. “We will care for the injured through every step of their recovery, and we will stand by the women and men of our armed forces as they bear the weight of this loss. They will not carry it alone. Because in Canada we take care of one another.”