"I'm saddened to share that there have been both fatalities and injuries as a result of an incident on the base," Defense Minister David McGuinty said on Saturday.
The Royal Canadian Mounted Police were involved in the investigation and described the situation as "very, very active and delicate".
The Canadian Forces Base is near Wainwright, Alberta, a town about 180km southeast of Edmondton.
The Canadian Armed Forces and federal, provincial and local authorities were co-ordinating the emergency response, he said. The nearby community of Wainwright was providing hospital and firefighting support.
The Municipal District of Wainwright said the fire crossed the base's fence earlier on Saturday and was spreading rapidly due to high winds. Firefighters from multiple jurisdictions were responding, and no evacuation order was in effect.
McGuinty said authorities were still working to determine what happened and expected to provide further information.
"A serious incident creating a major fire has occurred at CFB Wainwright, in Alberta," Prime Minister Mark Carney said earlier in a social media post.
"Our thoughts are with all the brave women and men affected," he said.
Alberta Premier Danielle Smith described the fire as "significant and tragic" and said it was affecting many military personnel.
Carney said the federal government was working closely with Alberta officials and local authorities. He said he and Smith were in close contact, as were their ministers and officials.
Smith thanked first responders and those providing care and support to those affected.
Canadian Conservative opposition leader Pierre Poilievre said he had spoken with Carney and the defence minister to offer support to those affected by the fire.
"Pray for Wainwright, everyone," Poilievre said in a social media post. He urged people in the area to follow emergency instructions and keep roads clear for first responders.
Neither Carney nor Smith provided details about what caused the fire or whether anyone was injured.
The fire came days before the province is set to vote on beginning a process that could lead to its seeking independence from Canada.
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