Montreal police arrested nine protesters on Sunday at a May Day march organized by the anti-capitalist group CLAC, as exchanges between demonstrators and police intensified.

<a href="https://twitter.com/hashtag/manifencours?src=hash">#manifencours</a> incident devant poste de police 20: gaz poivre, peinture, vitres fracassées <a href="https://t.co/wPU1peQBay">pic.twitter.com/wPU1peQBay</a> —@bahadorz

Police said protesters threw fireworks and tear gas in their direction in front of a neighbourhood police station on Ste-Catherine Street between Bishop and Mackay streets.

Two large police station windows were smashed by projectiles, and paint was thrown at the building.

Two police officers and two demonstrators were slightly injured.

May Day marchers shouted slogans while walking down Sherbrooke Street. (Bahador Zabihiyan/Radio-Canada)

A protester waves a signal flare during the annual anti-capitalist May Day march in Montreal. (Bahador Zabihiyan/Radio-Canada)

Montreal police used pepper spray to disperse the crowd, estimated at up to 300 people. Police said they gave the dispersal order in response to "criminal acts."

Orange smoke and the strong smell of pepper spay filled the area around Bishop and Ste-Catherine streets.

Orange smoke flares from a smoke bomb in front of the SPVM neighbourhood police station where two windows were smashed. (Bahador Zabihiyan/Radio-Canada)

Two meeting spots were set for the CLAC march: McGill University's Roddick Gates and Phillips Square.

Several demonstrators came from La Fontaine Park and the Frontenac metro station, prompting a heavy police presence as marches converged downtown on Ste-Catherine Street.

Police said 10 patrol vehicles had their tired punctured at the meeting point before the march began.

VIDEO: Police push a journalist aside as they chase a demonstrator before making an arrest

Une course poursuite à pied et en autopatrouille suivie d'une arrestation <a href="https://twitter.com/hashtag/manifencours?src=hash">#manifencours</a> <a href="https://t.co/I4W4xf4M5f">pic.twitter.com/I4W4xf4M5f</a> —@bahadorz

Prior to the march, CLAC said it planned to "disrupt commercial activity dominated by the local bourgeoisie" and indicated that "no interviews will be given to corporate media."

CLAC's May Day protest last year also resulted in disruption. Eighty-four people were arrested — 27 on criminal charges — and several people were tear gassed by police, including families and bystanders.

Police declared the march over around 6 p.m. at Place des Arts, where remaining protesters were dispersed.

Empty canisters of smoke grenades littered the streets after the May Day protest. (Bahador Zabihiyan/Radio-Canada)

A worker sweeps broken glass in front of a downtown Montreal police station that had its windows smashed. (Sean Henry/CBC)

FTQ march ended peacefully

Another May Day march organized by the Quebec Federation of Labour (FTQ) started at La Fontaine Park at around 1 p.m. before heading towards Jeanne-Mance Park.

The first day of May is marked around the world as a holiday and a time to celebrate and assert the rights of workers.

The FTQ and dozens of other organizations have taken the opportunity to call for Quebec's minimum wage to increase to $15.

Several protesters from the FTQ march later joined the CLAC protest.