TORONTO (AP) — Police are looking for a fourth person and haven't recovered the gun involved in a shooting at a rally for the NBA champion Raptors that wounded four people and sent thousands fleeing, authorities said Tuesday.

Toronto Police Chief Marc Saunders said they are looking for a male who was wearing a white button down T-shirt at Monday's shooting at city hall square, less than a block from where the players and Prime Minister Justin Trudeau sat on stage.

Police arrested three people who are now facing firearm charges, but the shell casings at the scene didn't match two guns seized. Shaquille Anthony Miller, 25, Abdikarim Kerow, 18, and Thaino Toussaint, 20 have been charged and made brief bail hearing appearances on Monday.

Droves of Raptors fans stampeded from the site. Those wounded by the gunshots didn't suffer life-threatening injuries.

Investigators did not discuss a possible motive.

Hordes of fans jammed downtown Toronto for Monday's parade, raising concerns about safety, lack of proper barriers and overcrowding as the city celebrated its first major sports title in more than a quarter-century. The parade ran three hours behind schedule as the team's double-decker buses had trouble getting through the throngs.

Mayor John Tory said the team owner and the city only had "three days" to prepare for the parade. Tory said the city's manager will work with police and the city's sports teams to review the parade to see how they can improve on it.