Ontario's Special Investigations Unit is investigating after an altercation at a Toronto demonstration left seven officers injured — including four who were sent to hospital but have since been released.

Community organizers told CBC News that the incident occurred after a person who appeared to be homeless and exhibited signs of mental health issues, who was not a part of the rally, had an "outburst." Police responded with dozens of officers rather than de-escalation tactics, they said.

Video posted on Twitter shows a man being pinned to the ground by officers.

Two people have been arrested, but there's no word on what charges they may face, according to police.