MONTREAL - Police have arrested about 150 demonstrators at the annual anti-police brutality march Thursday, which was reduced considerably in numbers about two hours after it kicked off.

Some property was damaged and a Future Shop electronics store was ransacked but police report that nobody was seriously hurt in the many exchanges throughout the evening, although one police officer reportedly suffered an injury to a finger.

Police will hold a news conference Friday at 10:30 where they promise to breakdown the number of arrests, injuries, and other damage caused during the march.

Police estimate that between 4,000 to 5,000 marchers took off with the crowd at around 6 p.m in the initially fast-paced march, but after the groups splintered apart, at around 7:45 p.m. one group of more committed demonstrators converged near McGill College and Ste. Catherine, while a larger group returned to Emilie Gamelin Park.

At around 8 p.m. police reported "heavy resistance" from a group of demonstrators on Berri between Ste. Catherine and Rene Levesque.

Soon afterwards, riot police stood in a line staring at the group, many of whom were chanting slogans at the police. Police reported that they used "chemical irritants" at the crowd after 8 p.m., likely referring to some form of pepper spray. 

Most of the roughly 150 arrests took place around that time, as police circled and arrested many members of a group which had convened on Berri and de Maisonneuve, in front of the provincial library. 

As of 10 p.m. police were still outside processing and identifying many of those that they had arrested.

Soon after those arrests took place, images from the standoff at Emilie Gamelin Park revealed a relatively laid-back scene as police and protesters appeared relaxed and in no rush to confront each other. 

By 8:45 p.m. the demonstrators had left the scene entirely and only a small group of police and curious onlookers remained on site.

At about 6:25 p.m. police had deemed the demonstration to be of an illegal nature and ordered the protesters to disperse. Police originally explained that they made the decision because two people had apparently been injured by projectiles tossed by the demonstrators.

A police rep also said that police feared that a motorist might be provoked by a demonstrator striking his car and react by driving into the attacker or a crowd.

Police also deemed that demonstrators on Sherbrooke were creating a serious danger, as the street is considered too large to close down to traffic.

After police ordered the protesters to disperse, some demonstrators were seen tossing projectiles at police cars, but appeared more determined to continue walking swiftly, many wearing clad in hoods and covering their faces as they walked west on St. Catherine towards the premier's downtown office.

Bands of protesters were seen as far as Doctor Penfield and Mountain. Earlier on, police reported that a group had briefly blocked access to the Concorde Bridge.

While many windows were smashed and at least one police car vandalized, there also appeared to be some resistance to the destruction within the protest group itself. In some instances demonstrators were seen restraining others in the act of vandalizing property.

One demonstrator attempted to torch a police car by putting a flare in the back seat, but another passerby immediately pulled the item out to prevent the car from catching fire, leading an officer to thank the man.

The column of demonstrators thinned as they walked to the west and the demonstration appeared to lose cohesion.

At about 7:30 p.m. police reported that the demonstrators had dispersed into various groups but some appeared to be re converging at the same spot where they started.

The police were seen videotaping the scene, apparently making a serious effort to detail the events, perhaps to make a video record that could lead to future arrests, not unlike that which occurred after the Stanley Cup riots in Vancouver last year.

Demonstrators unhappy with the way police do their work got the rally underway Thursday afternoon at 5 p.m. at Emilie Gamelin Park near the Berri metro station.

Many interviewed by journalist insisted that they support an orderly and peaceful march but police representative Ian Lafreniere said that many protesters, "make a peace sign with one hand while holding a rock in the other."

Since its inception in 1997, Montreal's annual demonstration against police brutality has become an annual ritual, associated with angry clashes, broken glass and usually ending with dozens of demonstrators getting rounded up and put into jail cells.

Prior to the demonstration police were alerting people to avoid the Ville Marie downtown area but could not specify the exact streets to avoid, as the demonstrators declined to offer a map of their route. They directed people to their twitter account @spvm for updates.

The protesters walked up Berri under the watchful eye of the police, who were equipped with sound grenades and pepper spray. They said they would arrest anybody vandalizing property.

Protester Dan Parker told CTV Montreal that he was at the protest to represent Occupy Montreal and wanted to express his disagreement with the police, which he described as "very violent."

Fellow demonstrator John Manicom said that he would not intervene if others smashed windows of large establishments but disliked seeing smaller concerns abused.

"I think it's really weak when people start busting up depanneurs and small businesses, but no, I'm not really concerned, I wouldn't stop anyone," he said. 

Last year police made 258 arrests, in fact about half of those participating were arrested. It was the second-highest total for arrests during the march. 

In 2010, police arrested 100 as four demonstrators were found with Molotov cocktails. Police eventually declared it an illegal demonstration and ordered it dispersed.

In 2009 police arrested about 200 participants. Eight were arrested before the action began for carrying dangerous objects.

In 2008 police made 47 arrests, a car was firebombed and police assaulted.

In 2007 the march went through Cote-des-Neiges and about 15 of the 400 marchers were arrested.

In 2006 police arrested 33, and as usual, a couple of businesses were vandalized and pepper spray was dispersed. One officer was cut by a broken bottle.

In 2005 police arrested five for tossing rocks and bottles.

In 2004 police arrested nine, a massive contrast to 2002, when police arrested 370, making it the biggest round-up in Montreal of since the War Measures Act of October 1970. Police made many of the arrests after windows were smashed at their headquarters on St. Urbain.

The 2001 demonstration was described as peaceful, police monitored from a distance while the 2000 protest ended in 100 arrests, with windows smashed on police stations, three McDonald's restaurants and several police cruisers.