Wednesday evening's 375th anniversary festivities weren't so celebratory for some Montrealers, as protesters — including police officers — hit the streets to try to sour the party mood.

Roughly 2,000 off-duty police officers gathered in protest Wednesday evening outside the Montreal Police Brotherhood office on Gilford Street.

They played loud music and honked horns, before marching off to City Hall in Old Montreal.

Officers have been without a contract since Dec. 31, 2014.

The police officers' union paid for giant billboard ads of Montreal Mayor Denis Coderre wearing a party hat, with the sarcastic phrase, "A mayor who shows contempt for his police officers for three years must be celebrated."

In a statement issued Wednesday, the Montreal Police Brotherhood said, "the police officers of Montreal wanted to illustrate, via shock advertising, that for three years, they feel scorned by the mayor and his administration."

Denis Coderre police protest billboard 375th anniversary

On Montreal's 375th anniversary, the Montreal Police brotherhood put up billboards targeting Montreal Mayor Denis Coderre. (CBC)

No special treatment, police say

Montreal police said they would treat Wednesday night's police protest like any other demonstration.

In 2014, the Montreal police department was criticized for failing to properly intervene during a protest by municipal workers at city hall.

Hundreds of municipal workers stormed the building and trashed council chambers. No one was arrested.

But Chief Inspector Alain Gagnon said the protesting officers would receive "no special treatment."

Gagnon said the police brotherhood informed the SPVM of its march itinerary and dismissed concerns that protesting police officers would be indistinguishable from on-duty officers.

While both groups wore camouflage pants and red caps, the protesters wore red vests, while the on-duty officers will wear bullet-proof vests marked "Police," as well as yellow arm bands.

Police protest

Montreal police officers gather in downtown Montreal to protest on the city's 375th anniversary. They have been without a collective agreement since 2014. (Sarah Leavitt/CBC)

Not everyone wants to party

In addition to protesting police officers, a number of other demonstrations were also planned to coincide with Montreal's 375th birthday celebrations.

Affordable housing activists took to the streets Wednesday morning.

Another protest targeted the city bylaws dealing with horse-drawn calèches, pit bull-type dogs and other animal control issues.

Firefighters, who had also been without a contract since 2014, reached a tentative agreement Wednesday, so they won't be protesting. 

The union representing 2,400 firefighters confirmed the deal.

With files from CBC's Ainslie MacLellan, Sarah Leavitt