He suffered injuries to the upper body and he was transported to hospital, say police.
Police are still looking for the suspect, who fled before officers arrived.
Witnesses told police the victim had been with a friend. Investigators are trying to determine what the victim’s relationship was with the friend.
A large perimeter is in place as officers investigate and speak to witnesses.
Ste-Catherine Street is closed between Bishop and De la Montagne streets, while Crescent Street remains closed between René-Lévesque and De Maisonneuve boulevards.