People have been killed and injured in a fire at a military base in the Canadian province of Alberta, the country’s defence minister has said, with officials yet to clarify what caused the incident.

Defence minister David McGuinty said a “serious” incident at Canadian Forces Base Wainwright had caused a major fire, though he provided few details and no precise figures for how many people had died or been hurt.

“I’m saddened to share that there have been both fatalities and injuries as a result of an incident on the base,” McGuinty said at a news conference in Ottawa.

McGuinty said the Royal Canadian Mounted Police were involved in the investigation and described the situation as “very, very active and delicate”.

He said authorities were still working to determine what happened and expected to provide further information, but suggested it was a major and unprecedented event.

“I cannot recall an incident like this in recent memory,” he said.

The Royal Canadian Mounted Police said officers were called shortly after 4pm local time (10pm GMT) on Saturday after reports of a fire in a training area at the base, which lies about 180km (120 miles) south-east of the provincial capital, Edmonton.

The Municipal District of Wainwright said the fire crossed the base’s fence and was spreading rapidly because of high winds, and that firefighters from several areas were responding. No evacuation order was in effect, but residents were asked to avoid the area, keep roads clear and stay away from the Wainwright Health Centre unless they needed critical care. Gusts of up to 100kmph hit large parts of the province during the day.

Patients were taken to hospitals across Edmonton because health facilities in Wainwright were overwhelmed, according to Dr Warren Thirsk, an emergency physician at the city’s Royal Alexandra Hospital.

“This number of patients would overwhelm the city of Edmonton,” Dr Thirsk told CBC News. “It is more patients than any of us want to count right now. It’s a disaster. It’s a one in every 15 to 25-year disaster.”

Prime minister Mark Carney said in a social media post: “Our thoughts are with all the brave women and men affected.”

Alberta premier Danielle Smith said in a post on X that the province was “learning of a significant and tragic fire that is affecting many of our brave military personnel”.

Opposition leader Pierre Poilievre said in a social media post: “Pray for Wainwright, everyone.”

General Jennie Carignan, the chief of the defence staff, said in a post on X: “We are dealing with a serious incident at CFB Wainwright, and are fully engaged with federal, provincial and local authorities.”

The base is one of Canada’s busiest military training sites, where soldiers prepare for combat operations, and it is home to the Canadian Manoeuvre Training Centre and the 3rd Canadian Division Training Centre.

The fire disrupted advance voting ahead of Monday’s referendum on whether Alberta should begin a process that could lead to independence from Canada. Elections Alberta said two polling locations, in Lloydminster and Vermilion, closed early on Saturday and that the ballots were transported securely.