MONTREAL - A Montreal criminologist said she believes gang activity is at the root of two separate shootings in Montreal North that left one man dead and three others injured.

Officers were called to the corner of Matte Ave. and Pierre St. just before 9:30 p.m. Thursday to investigate the sound of gunfire. Police found three men, aged 17, 26 and 42--all shot in the lower body. They were rushed to the hospital, but none of their lives were threatened.

Investigators and the K9 unit were called to the scene as police taped off a large perimeter. The owner of a nearby depanneur told CTV News he had heard gunshots earlier in the day.  

An hour after discovering the three gunshot victims, Montreal police found the body of another man. He had also been shot nearby in an alleyway on Lapierre St. -- this time, though, the shooting was fatal.

The man's death has been classified as a homicide, the city's 16th of the year. The victim, a 23-year-old, has not yet been identified, and the investigation into his death is continuing.

"The Major Crimes Unit has taken charge of that investigation, and there's no suspect in that case," said Montreal police spokesperson Raphaël Bergeron. 

The three surviving victims are being interviewed by investigators, said Bergeron. They are known to police. 

Officers say the two incidents are related, but have remained tight-lipped about the case.

 Criminologist Maria Mourani, however, said the shootings have all the markings of gang turmoil, with one gang pitted against another.

"Unfortunately, when we talk about street gangs, they don't care about collateral victims," said Mourani, who has researched and written about gang activity in Montreal and elsewhere.

Mourani said gangs in Montreal typically keep the peace by developing pacts. Nonetheless, any gang violence poses risks to the general population.

 "If they have a problem, they're going to fix it, and they don't care about the people around, so this is the problem with the gangs," she said. "They're also impulsive. They react fast, and if they have to fix a problem, they're going to do it."