THE CANADIAN PRESS -- MONTREAL - Anti-police demonstrators 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.

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."

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

Minutes before the demonstration turned unruly, the crowd paused at the scene of the shootings just outside the Universite 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.

"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.

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 Surete du Quebec (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.

By Andy Blatchford, The Canadian Press