The two people killed in the shooting rampage were just 10 and 18 years old, according to police.
The girl and young woman were among 15 people shot Sunday night in the city's popular Greektown neighborhood, police Chief Mark Saunders said.
Now, as the wounded recover from their injuries, investigators are trying to understand what prompted the shootings.
Mayor of Toronto , John Tory, said he was "outraged that someone has unleashed such a terrible attack on our city and people innocently enjoying a Sunday evening."
"We have a gun problem in that guns are readily available to too many people," Tory said. "The police are doing their best, but they're operating under extraordinarily difficult circumstances to deal with these guns. And we'll see what they conclude from this case, but it's evidence of a gun problem, clearly."
