Three arrests have been made after 4 people sustained non-life-threatening gunshot wounds at Monday's rally celebrating the Raptors' championship, Toronto Police Chief Mark Saunders said hours after the incident.
Saunders has yet to give details about the arrested suspects.
"It is disappointing and I'm sure a source of anger for more than just me that anyone would carry a gun and discharge it at what was otherwise a joyous celebration," Mayor John Tory said in a statement.
"I hope those responsible will be held to account to the full extent that the law permits. I want to commend and thank the millions of other people who happily and peacefully celebrated our beloved Toronto Raptors," the mayor said.
The Raptors were celebrating their first NBA title, and the first by a Canadian team, four days after Toronto completed a six-game win in the NBA Finals against the two-time defending champion Golden State Warriors.
A reported 1.5 million parked Toronto's downtown for the Raptors' parade and subsequent rally at City Hall.
The shootings occurred at Nathan Phillips Square, adjacent to City Hall. More people sustained minor injuries attempting to flee the scene after the shots were heard.
Tory and Canadian Prime Minister Justin Trudeau were with the Raptors players on stage at the rally when the shots occurred. The festivities were briefly paused before resuming.
Trudeau's spokeswoman declined to comment on the fact that the nation's leader was nearby to a shooting.