TORONTO -- A prestigious private school where a student was allegedly sexually assaulted did not report the incident to the Toronto police, a spokeswoman for the force said Thursday, adding that a criminal investigation was launched only after officers were contacted by the media.

Police did not release any details about the incident, which allegedly took place at St. Michael's College School, an all-boys Catholic institution that teaches grades 7 through 12.

In an email to parents, the school's principal said they had been made aware of "two very serious incidents" that were in clear violation of the student code of conduct.

"The administration was informed about these incidents on Monday of this week and immediately began an internal investigation that included informing police and meeting individually with the students involved and their parents," Greg Reeves wrote in the note sent Wednesday afternoon.

"Our concern is first and foremost with the safety and well-being of our students and we are shocked and heartbroken that such incidents have taken place at our school," he said.

Const. Caroline de Kloet said the school had contacted police on Monday to seek advice on how to deal with an incident that was not the alleged sex assault.

"Advice was provided to the school and no further action was taken or received," de Kloet said.

She said the force began investigating on Wednesday after receiving media inquiries about an alleged sex assault.

St. Michael's is run by the Basilian Fathers with roots dating back to the Congregation of St. Basil in France that is a "fully independent, Catholic high school," according to its website.

"We are deeply saddened by the events that have come to light over the past days," said Rev. Thomas Rosica, a spokesman for the Basilian Fathers. "Our primary concern in all of this situation is the protection of students, young people and vulnerable persons."

Rosica said the organization is working with school officials and authorities to establish a timeline of events.

Two police sources said the incident the school discussed with officers on Monday involved members of the basketball team bullying a student and soaking him with water. Those sources say there was another incident involving the football team where a group of boys held down another student and allegedly sexually assaulted him with a broom handle. Both incidents were captured on video and circulated among the students at the school.

In a rare move, police released a statement Wednesday night saying investigators had determined the video of the alleged sexual assault met the definition of child pornography.

"Anyone who has this video is in possession of child pornography," police said. "The video must be deleted immediately and cannot be shared with anyone."

Det. Sgt. Paul Krawczyk, who runs the child exploitation section within the sex crimes division at Toronto police, said they decided to act proactively and warn both parents and students about the severity of possessing and sharing the video.

"It shows the alleged sexual assault of a child," he said in an interview.

Krawczyk said getting the video removed from the internet will be almost impossible, and in some cases police are worried about losing evidence.

"But we have the evidence we want," he said. "I'd rather lose potential evidence and save a victim from having this sent around more. It's trying to stop that little hole of water from becoming a burst dam."

Krawczyk said he wants both parents and students in general to be aware of the perils of sharing sexually explicit videos.

"There are charges at play, like non consensual distribution of intimate images," he said.

St. Michael's is known for its athletic programs, and alumni include hockey greats Frank Mahovlich, Dave Keon and Tim Horton. Other alumni include Ottawa Senators owner Eugene Melnyk.