Neighbours called police at around 10:30 p.m. after hearing gunshots near the intersection of 2nd Avenue and Everett Street, which is in the borough's François-Perreault district.
Officers found a man in a vehicle that had several bullet holes in the window.
He was taken to hospital in critical condition and later died of his injuries.
A few hours later and a few kilometres away, residents living on 14th Avenue in St-Michel called police to report a man spraying gas on an SUV.
Residents intervened and the suspect fled without starting a fire.
Police are trying to find out whether the two incidents are linked.