Montreal police could have avoided hundreds of thousands of dollars of overtime incurred after a summer riot in a northern borough if the area was staffed properly, says the force's union.

Chaos reigned in Montreal North the night of the riot. (CBC)CBC News has learned that policing costs in Montreal North following the Aug. 9 shooting death of a teenager have added up to more than $930,000, mostly in overtime hours, according to documents obtained through the Access to Information Act.

The borough was turned upside-down after Montreal police shot and killed Fredy Villanueva, 18, during a late-night confrontation in a parking lot.

Looters ransacked stores and businesses and rioters caused thousands of dollars of damage in the multi-ethnic, working-class neighbourhood.

The situation would not have been so expensive for police had the appropriate authorities been on the ground in the borough before violence exploded, said Yves Francoeur, president of the Montreal Police Brotherhood.

"The crime rate is very high," in Montreal North, Francoeur told CBC News. "We're talking about a population of roughly 85,000 citizens," being safeguarded by only three teams of two officers, when there should have been at least five pairs.

Vandals torched several cars that were parked on the street. (Canadian Press)Before Villanueva's death there was never more than seven officers patrolling the borough at any given time, not enough to build positive rapport with the community, "to visit stores, to visit [the] metro, even if only to talk with people on the street," Francoeur said.

Villanueva's death and following riot irritated tense relations between police and residents in the borough, especially among young people.

Police presence has since visibly increased with 10 more officers assigned to the area.

In a one-month period, officers amassed nearly 14,000 hours of overtime, at a cost of $840,000. Another $100,000 in additional expenses was claimed.

The expenses are a necessity, said Claude Dauphin, executive committee member in Montreal in charge of public safety.

"It's not a matter of money right now" because the situation is still fragile in the borough, Dauphin said. "It's a matter of making sure we're working well with those different communities."

Montreal butcher Carmene Ruzzo spent days cleaning up his vandalized store. (Peter McCabe/Canadian Press)The city of Montreal is still debating whether to permanently increase patrols in the area.

The province has already advanced $50,000 to a coalition of community groups dedicated to outreach efforts.

The money will be used to host youth workshops and launch a local newspaper, among other things, said Victor Henriquez, a spokesman for Solidarity Montreal-North.

"We want to be sure that people understand that if you want to be listened [to], you don't have to do it in a violent way like last time," he said.