It happened while crews were responding to a blaze in the city's St-Laurent borough.
Serge Tremblay, director of the Montreal fire department, told a news conference Friday evening that the 38 year firefighter was struck by a pumper truck.
Tremblay said the victim's name was being withheld pending the notification of family members.
He said two other firefighters were being treated in hospital for shock.
Tremblay said police, the fire department and the Committee on Health and Safety were all investigating the incident.