Classes scheduled to take place inside the J.A. DeSeve building at UQAM have been cancelled on Thursday, as the school is forced to clean up the disaster left behind by student occupiers who had barricaded themselves on the premises.

The protesters had been hoping to occupy the J.A. DeSeve building at l'Université de Quebec a Montreal throughout the night, but after four hours police refused to let them stay any longer.

The events at UQAM began Wednesday morning when demonstrators, some of them wearing masks, stormed into classrooms, claiming the classes being taught were violating student votes to boycott classes.

The demonstrations degenerated into multiple fistfights between students who wanted to attend class and the demonstrators.

Police called to break up fights

Around 2 p.m. UQAM adminstrators called police for assistance in removing the protesters and enforcing a court injunction preventing protesters from blocking entrances to buildings at UQAM.

When police arrived and began breaking up fights and arresting people, many teachers took offense and formed a human chain to isolate police officers from students.

However by 4 p.m. police had arrested 21 people and left the school.

Communications professor Jean-Hugues Roy said many teachers were in a difficult position.

"We don't like masked people telling us, intimidating us or our students, but we don't like police inside our walls," said Roy.

Montreal police commander Ian Lafreniere said several teachers then tried to get the students out of jail, but did not seem to understand how the criminal justice system works.

"At a certain point there were some teachers that showed up at the detention centre mentioning that they were there to negotiate the release of the students," said Lafreniere.

"That's not really what's going on. We're talking about the criminal code now. This is going to be the judge that will decide that.

"It's not a game, it's not a negotiation. It's a criminal offence."

The 22 protesters were released after agreeing to appear in court. Police are recommending charges of misdemeanours and unlawful assembly.

Demonstrators returned with hammers, nails

Soon afterward demonstrators moved into the building and began constructing barricades in hallways, and blocking escalators and stairways with tables and chairs.

Students leaving their evening classes had to thread their way through a maze of debris in order to exit the building.

The occupiers eventually forced most people who were not sympathetic to their cause out of the building, telling various reporters that they did not want anyone taking pictures as they committed numerous acts of vandalism.

One protester said they were occupying the building "not only to protest, but also to reappropriate this space, which is a place of learning, in order to repair the harm that was caused [by the arrests earlier in the day]."

After receiving numerous calls from protesters and from teaching staff at UQAM to abandon the injunction and to let protesters remain in place, the rector of the school refused.

Second call to police

At 10 p.m. rector Robert Proulx said the protesters were in the wrong and that it was entirely appropriate to ask police to remove them.

"The actions taken [Wednesday] are the work of a minority, are unacceptable and are strongly denounced by this University. It is responsible, and with a goal of maintaining the openness of the school and the security of all people that we have taken the decision to call upon the Montreal police force," he wrote.

Four hours after the occupation began police began breaking their way through the barricades and locked doors, and some protesters fled.

In their flight some protesters vandalized police cars and one person assaulted a police officer.

Police arrested five people.

Some protesters may not be students

Ian Lafreniere said he did not believe that all of the protesters setting up barricades at UQAM were students.

"We found on the scene indications that these people, some of them are students, but others may not be.

"They had hammers, nails. These people were prepared for some sort of action," said Lafreniere.

He added that police are spotting some of the same people at multiple protests.

"Every time we have some sort of disturbance like this they are people who take advantage of the situation to rile things up.

"There are people who go from demonstration to demonstration with no goal other than to make it worse."

With a file from The Canadian Press