A Canadian military convoy opened fire on a vehicle approaching at high speed, killing an employee of a private security firm and injuring three others, officials confirmed Thursday.

The convoy, part of Canada's Provincial Reconstruction Team, was leaving Kandahar Airfield and heading for Kandahar City on Wednesday afternoon when a vehicle approached at high speed, Canadian Forces spokeswoman Capt. Josee Bilodeau said in a statement.

The vehicle "was perceived as a threat" and warnings were issued but a shot was fired when the vehicle failed to stop, said Bilodeau.

"These multiple warnings were not heeded to and a shot fired in direction of the vehicle was required, after which, the vehicle stopped,'' she said.

On-site medical assistance was administered, and all individuals were then transported to the medical unit at Kandahar Airfield for treatment.

The vehicle belonged to Compass Security -- a private company with operations throughout the Middle East, Africa and Central Asia, from Iraq to Afghanistan.

"Incidents like this one are regrettable, however, our forces took all reasonable steps to prevent injury to the individuals and to protect themselves,'' said Bilodeau.

The military has offered its condolences to the family of the person who died.

The identities of the dead and injured have not been released.

With files from The Canadian Press