Police in Canada 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 left four people wounded and sent thousands fleeing less than a block from where the players and Prime Minister Justin Trudeau sat on stage.

Toronto Police Chief Marc Saunders said Tuesday they are looking for a male wearing a white button down T-shirt. Police arrested three people who are now facing firearm charges, but the shell casings at the scene didn't match two guns seized.

Droves of Raptors fans ran from the shooting Monday in and around city hall square. Those wounded didn't suffer life-threatening injuries.

Investigators did not discuss a possible motive.