On Aug. 18, a large number of people opposed to Quebec's proposed pension reform bill assembled outside of city hall.
Some lit a fire in the middle of the street. A group of protesters then proceeded to barge into city council's chambers, flipping over furniture and throwing papers around.
After the incident, Montreal police chief Marc Parent said he was disappointed that members of the police force allowed protesters to barge into city hall.
He said he could not help but notice there were shortcomings in security.
Parent assembled a team of investigators to look at how police handled the protest.
The city has already taken action against other employees, suspending firefighters and city workers who took part in the demonstration.
On Tuesday, Ronald Martin, head of the Montreal firefighters' union, was suspended six months without pay.
Six firefighters also lost their jobs.