The incident, which police have confirmed as the city's fifth homicide, occurred at about 6 p.m. last night near the intersection of Pierre Gaulin and Jean Tavernier streets.
According to Const. Daniel Lacoursière, the victim was getting out of his car when he was approached by one or more men and shot at least once in the upper body.
The victim, a 69-year-old-man, was taken to the hospital and pronounced dead.
Montreal police are not confirming reports from Radio-Canada that the victim was Gaétan Gosselin, the former brother-in-law of Raynald Desjardins. Desjardins is believed to be a high-ranking figure in Montreal's mafia.
Major crimes unit investigators tracked down two suspects on Brunet Street in Montreal North about four hours after the incident.
Officers are expected to obtain a warrant to search the Montreal North home of one of the suspects.
Montreal Police spokesperson Yannick Ouimet said both men are being held at a detention centre.