Toronto Police Chief Mark Saunders is calling for a public discussion about acceptable behaviour, following an altercation between police and a screaming crowd that took place downtown over the weekend.

Saunders made the statement during a Wednesday morning news conference about a confrontation over the weekend.

"What we saw over the weekend at Yonge and Dundas Square was extremely disturbing," Saunders told reporters.

"We saw behaviour that was dangerous, behaviour that was reckless, behaviour that could have caused extreme, serious injuries."

Officers were called to the downtown square on Saturday night following multiple reports of a person with a gun, Saunders said. Thousands were in the downtown core for Nuit Blanche at the time, but there is no indication of a connection between the all-night event and the confrontation.

When officers arrived, a fight broke out. Many people rushed to get away from the area, and a woman was trampled by the crowd, he said.

Police took a person into custody during the fight, who Saunders said was carrying a gun, a baton and a knife.

"At that point, the mood of the crowd changed," Saunders said, referring to a confrontation that was caught on camera.

"We saw young people... become aggressive and threatening."

Video captured during the incident shows a screaming crowd taunting Toronto police officers who can be seen backing away from the crowd. Officers are seen slowly moving through glass doors that lead to an underground parking lot.

Saunders said people in the crowd threw bottles and other objects at officers. During the incident, members of the crowd were laughing, smiling, booing, and cheering, he said.

Saunders added that there were young children present at the time.

The role of police is to investigate what happened and bring offenders before the court when there is sufficient evidence, Saunder said.

"But this goes well beyond the police. I believe there needs to be a wide-ranging public discussion on what is acceptable behaviour in the public of our city," he said.

"This type of behaviour can never be tolerated."

He said it should be "socially unacceptable" to be impaired in public and engage in or encourage violent behaviour as "some sort of performance.

"We're very lucky that there were no serious injuries here."

Saunders asked anyone who took photos or recorded video of people throwing objects at the police and the public at the square Saturday night to come forward to police.