McGill University's principal has launched an investigation after a massive student tuition protest reportedly turned violent on Thursday night, and riot police were called in.

Principal Heather Munroe-Blum, in an open letter published on McGill's website, said she's asking the dean of law, Daniel Jutras, to conduct an independent investigation into what she called "disturbing" events at the school's downtown Montreal campus. Jutras is to report back with his findings by Dec. 15.

"The presence of riot police on our campus is shocking," Munroe-Blum said. "We, as a community, need to fully understand the events and the responses to them and I trust Dean Jutras will conduct a thorough, impartial review."

Some students and staff are accusing Montreal police of overreacting to what they call a largely peaceful protest.

“This was a very violent example of what I would call police brutality,” said Greg Mikkelson, an associate professor in McGill’s department of Philosophy and the School of Environment.

Mikkelson said he was clubbed with a baton and pepper sprayed in the face as he was walking on the university campus to the daycare to pick up his daughter.

“I had just stopped to watch what was going on, and the police just walked up to me and attacked me,” he said.

Mikkelson said he heard no caution from police before three officers rushed toward him.

“I don’t know why they had to be here. I don’t know why any police had to be here. I think there are a lot of questions that have to be answered,” he said.

Munroe-Blum said she was not on campus at the time, but was told that a group of protesters, some wearing masks and hoods, unlocked the James Administration Building and forced their way into the principal and provost offices and a reception area, pushing staff in the process.

She said campus security managed to usher most of the protesters out, but a few refused to leave and had to be carried out. At the same time, she said, a protest grew outside the building, apparently encouraged by social media messages from the protesters inside. The protesters blocked all exits to the building and employees could not leave.

"It was clearly a tense, stressful situation," Munroe-Blum said.

She said security called Montreal police.

Munroe-Blum said university officials were able to negotiate with protesters inside the administration building, convincing them to leave peacefully in exchange for facing no disciplinary action. The situation that erupted with Montreal police and protesters outside was entirely directed by Montreal police, she stressed, not university administration.

Riot squad deployed

Police said their involvement started earlier in the evening after some of the protesters acted aggressively in front of Premier Jean Charest's office on McGill College Avenue.

“When the peaceful protest was over, we had problems,” said Montreal police spokesman Ian Lafrenière. “Not with all the people, just a small group of individuals trying to take advantage of the situation to do something stupid.”

People starting throwing objects, including boat flares shot from a pistol, in the direction of officers.

Lafrenière said that was when the riot squad was deployed. Two people were arrested in connection with the projectile incident.

As the crowd dispersed, a group of people ran toward the McGill campus, he said. The university contacted police, and said members of that group were acting aggressively and need to be expelled from the property.

Arrests made

At that point, riot officers moved on to campus. Two more people were arrested there.

Ross Brown was outside McGill’s administration building just before the riot police came into the square. He said he saw a group of people rush toward the building and force bike patrol officers to retreat before riot squad officers arrived.

A video Brown shot of the event shows police officers raising up their bikes and moving backwards away from the group.

Lafrenière said he witnessed confrontations himself Thursday night, but could not comment specifically on the incident involving Mikkelson. He encouraged anyone who felt police used excessive force to contact the professional ethics commission.

“If it happened, honestly, I’m really sorry about it. I’m really sorry to hear that,” he said.

“This is not the way we want to hear about [possible problems.] We got there yesterday, we thought it generally went right, but if specific cases like this happened, there’s always the déontologie policière.”