Investigators say Denis Allkushi, 25, came into conflict with a client while working in an outdoor parking lot on Bleury Street near President Kennedy Avenue.
Allkushi allegedly grabbed the victim by the collar and pointed a gun at him. The suspect then turned the gun toward the ground and fired, police say.
Allkushi was in a black 2004 Toyota Echo with the Quebec license plate K57 GKC.
A warrant has been issued for his arrest.
Police say Allakushi has brown hair and brown eyes and the word "Gemini" tatooed on his neck. He could be armed and dangerous.
Anyone with information is asked to contact police at 514-393-1133.