Toronto police say they are investigating after receiving two videos Monday allegedly showing a St. Michael's College School student being assaulted with a belt.

Insp. Dominic Sinopoli, who heads the force's sex crimes unit, said the alleged incidents appear to all involve males, but wouldn't specify when asked at a Tuesday news conference if they occurred at the school.

"We're just being extremely cautious with everything that we receive, being extremely thorough," he said of a sexual assault investigation launched at the Catholic, all-boys school last week.

Sinopoli added police have reason to believe there are more victims and videos out there, and urged anyone who has not already come forward to contact them.

"Sometimes students may be a little reluctant to come to police," he said, noting if witnesses can't "muster the energy or the courage" to come forward then they can do so through the school or Crime Stoppers.

Sinopoli said the alleged incidents captured on video may be duplicates of what the school has already sent to police and that it's not immediately clear when they were taken.

He added that investigators haven't received any information to suggest a "fight club or any culture of hazing" at the school.

A former St. Mike's student told CBC News last week that he wasn't shocked to learn about the allegations because "that's the culture at the school." Kyle Fraser claimed he left the school, in part, because of the bullying he faced.

Insp. Dominic Sinopoli, the head of Toronto police's sex crimes unit, said Tuesday a belt was used as a weapon in an alleged assault caught on video. (Tijana Martin/Canadian Press)

Investigators received the latest videos the same day police charged six students with being involved in a gang sexual assault at the school.

Sinopoli has said that incident at St. Mike's started as hazing before veering into the "criminal arena."

The Canadian Press spoke with police sources who confirmed that the charges filed Monday involved a group of students, aged 14 and 15, on the football team who allegedly pinned down another student in a locker room and sexually assaulted him with a broom handle.

Three St. Michael's College School students, left, made a brief court appearance on Monday in Toronto. (Pam Davies/CBC)

The identities of the six teenage boys charged are protected under the Youth Criminal Justice Act. They are facing multiple criminal charges including assault, gang sexual assault and assault with a weapon.

They appeared in a youth court Monday afternoon and were released on bail. They are scheduled to appear again on Dec. 19.

St. Mike's, which has expelled eight students in connection with the allegations, said it supports the police force's move to file criminal charges. It's unclear if any of the eight are among those who have been charged.

Police are now investigating a total of six allegations involving students at the school, which has students in Grade 7 to 12.

St. Michael's College School in Toronto is at the centre of an unfolding scandal. (Frank Gunn/Canadian Press)

The school ​has also launched a third-party investigation into the present situation and past incidents. Principal Greg Reeves said he hopes a preliminary examination will be done by spring with a more in-depth investigation to wrap up next summer.

"This is an excellent learning experience, it's a teaching moment in particular for the school's principal," Sinopoli said Tuesday.

Last week, police revealed the school didn't report the allegations and that a criminal investigation was launched only after officers were contacted by the media.

Reeves explained the reason he didn't report the video to police right away is because the alleged target of the attack had not yet told his family about the incident. The principal told reporters Monday that he called the boy's parents.

"If [Reeves] could walk this back, he would likely do this very differently," Sinopoli said, noting the school should have reported the incident to police immediately.

St. Michael's College School principal Greg Reeves says there is a problem at his school and that it needs to do better. (Christopher Katsarov/Canadian Press)

Mayor John Tory commented on the St. Michael's situation Tuesday, telling reporters what has transpired is "very sad, very tragic and very unacceptable."

"We're going to have to look for as well is leadership from all fronts — from parents, from the administration of the school and from the community and the police and others — to make sure that we learn from this and that justice is served," he said at city hall.

We have cancelled 2018 mid-year assessments & all events w/ external groups, teams, & public performances for rest of 2018. Instead, students will participate in workshops & discussions on issues that have arisen. <a href="https://t.co/Jjm8iQ1NbO">https://t.co/Jjm8iQ1NbO</a> —@SMCS1852

A private, emergency alumni meeting will be held at the school Tuesday evening.

St. Mike's, which is known for its athletic programs, also announced this afternoon that all events involving external groups, sports teams, and public performances will be cancelled for the remainder of 2018 because of the "emotional toll" the allegations have taken on students.

"Throughout this time period, students will also participate in workshops and discussions pertaining to the issues that have arisen," the school said in a statement on its website.

"We remain focused on our entire student body — their safety, care, and well-being are our main priority."

With files from CBC's John Rieti and The Canadian Press

Here's a timeline of events based on information provided by St. Michael's College School and Toronto police: