Police received reports of gunfire at a parking lot on Jeanne d'Arc Avenue north of Ontario Street around 9 p.m.
Officers arrived at the scene and found shell casings on the ground. A search of the area found a man, with superficial cuts to his head, who offered police a convoluted account of how he got his injuries.
"He had a fuzzy story of what happened," said Simon Delorme, a media relations officer for the Montreal police department.
The man was taken to hospital.
Police then came across two other men who reported being mugged by a group of four armed men. The two were questioned at length by police, who continued their search for the four suspects.
A forensics unit and a police dog team spent the evening on the scene.
"Was it an incident related to narcotics? A drug transaction turned bad? A conflict that finished as it wasn't supposed to? This is what investigators are trying to establish at this time," said Delorme.