McGuinty's statement came amid rising concerns after the fire crossed the base fence early Saturday, spreading rapidly under high winds.
The Canadian Forces Base Wainwright, 180 km southeast of Edmonton, hosts the Canadian Manoeuvre Training Centre and the 3rd Canadian Division Training Centre, making it one of the country's busiest training sites.
The Municipal District of Wainwright said no evacuation order was issued and that firefighters from multiple jurisdictions responded, while the local community supplied hospital and firefighting support.
Prime Minister Mark Carney, Alberta Premier Danielle Smith, and opposition leader Pierre Poilievre all expressed condolences and pledged cooperation, noting that the federal government is working closely with provincial officials.
Investigators will publish further details once the Royal Canadian Mounted Police and military authorities determine the cause of the blaze.