Anti-police brutality demonstrators in Montreal marched to the site of a tragic shooting Wednesday night where two people, including an innocent bystander, were killed by officers' bullets.

Then they began smashing windows.

Members of the crowd picked up materials from a construction site and hurled them as projectiles.

Patrick Limoges, 36, was killed by a stray bullet. Patrick Limoges, 36, was killed by a stray bullet. Radio-Canada

They pelted bricks and chunks of broken concrete at about a dozen commercial windows, including restaurants and coffee shops. Several of the windows shattered.

An outdoor portable toilet was overturned and tossed into the street. Buildings, streets and at least one onlooker were splattered with pink paint tossed by demonstrators.

Many of the 200 protesters were dressed head to toe in black or wore black bandannas to conceal their faces, garb commonly worn at rowdy protests.

They chanted slogans and held signs denouncing police violence. One giant banner said, "Never again."

Probe system criticized

Police accountability in Quebec has come under fire in the wake of a handful of deadly police shootings in past years.

One of the most high-profile cases involved Fredy Villanueva, an 18-year-old Montrealer who was shot dead in 2008 in a parkside confrontation with two local officers. In the Villanueva case, provincial police were asked to investigate the incident and concluded the Montreal officers acted appropriately.

A separate coroner's inquiry into the Villanueva shooting has yet to release its findings.

Since Villanueva's death, community activists and the province's own ombudsman have called for a major overhaul of the way police investigate injuries and deaths during their operations.

Unlike a handful of provinces, including British Columbia, Alberta and Ontario, Quebec does not have an independent, civilian-run agency with the authority to investigate cases in which police actions result in injury or death. Under the current system, police investigators from one force probe incidents of civilian injury involving other forces.

In a 2010 report, Quebec ombudsman Raymonde Saint-Germain urged the province to create a stand-alone, civilian investigative unit, instead of allowing police to investigate each other.

"This is the only way to get the confidence of the population and to have a process that is credible and impartial," Saint-Germain said at the time.

Dozens of officers on motorcycles kept an eye on the crowd in a city with a history of violence at anti-police brutality protests.

Later, officers in full riot gear marched through a downtown street banging their batons on their shields in unison, forcing a large gang of demonstrators to disperse.

Some protesters quickly shed their dark clothing to blend back in with the peaceful activists.

In the end, this protest was quieter than recent anti-police brutality events in Montreal. The police department said there were no arrests, no injuries and four windows were smashed.

This march was prompted by tragic events Tuesday, when police shot and killed two people: a homeless man allegedly wielding a knife and a bystander who was on his way to work at a nearby hospital.

Vandalism warranted: protester

Minutes before the demonstration turned unruly, the crowd paused at the scene of the shootings just outside the Université du Quebec a Montreal. One man speaking into a megaphone reminded fellow protesters that the blood of the victims was still visible on the rain-soaked sidewalk.

"We don't forgive, we don't forget," the masked man shouted — in both English and French — into the megaphone.

His remarks prompted cheers and whistling from the crowd around him.

A demonstrator who gave his name as Nico Block said the damage the protesters caused was warranted.

He said that's the price for the two lives lost at the hands of police.

"This is the kind of demonstration that is costly and embarrassing for the city and that's a good thing," said Block. "Sometimes the cost of slaughtering people has to be manifest[ed] in a way that has an actual palpable cost for the city."

"I'm here to demonstrate against police impunity," said another protester who would only call himself George.

"I'm here to protest in favour of . . . an independent inquiry committee, because cops investigating cops over these shootings — it just doesn't work, man."

Numerous critics are calling for a change in the way Quebec handles police-related shootings.

Provincial police investigating

Any shooting in the province involving an officer's gun is investigated by an outside police force. Provincial police have taken over the investigation into Tuesday's deaths.

Critics say the system lacks transparency and police investigators ensure their colleagues never have to face justice.

"There was another murder by police and the other murders that happened in the past were never punished — I think that's a problem," demonstrator Jean-Luc Simard said Wednesday before the march.

"We know the same thing is going to happen again — the Sûreté du Québec [provincial police] will justify this assassination."

In a bizarre twist, reports emerged just as the protest began that Quebec provincial police officers were involved in another shooting in the town of Rawdon, Que.

Two officers intervened to help a man who, police say, had been attacked. After an altercation, provincial police say one of their officers fired at a man they allege was causing the disturbance.

The man was brought to hospital and his injuries were not considered life-threatening.