Police now believe the incident on Saturday night was an exchange of gunfire between two people targeting each other.
Toronto Police Deputy Chief Frank Barredo said investigators recovered two firearms after the shooting that was reported at 8:12pm near St Clair Avenue West and Arlington Avenue, where the Salsa on St Clair festival was underway.
No suspect or suspects had been arrested by the time of a late-night news conference, where Barredo confirmed both of the dead victims were men.
Officers initially urged the public to avoid the area before later announcing the scene had been secured.
"There was some concern about an active shooter. That turned out not to be the case," Barredo said. But the two gunmen involved in the shooting "indiscriminately put vast numbers of people in danger".
Valerie Rodriguez said she was sitting outside a nearby restaurant when people suddenly began screaming and running.
"A bunch of people … told us to lay down onto the floor," she said.
"We got scared because we didn't know exactly what was happening."
Festival vendor Patsy Gutierrez said she was serving customers when she saw "a huge wave" of people fleeing.
"Everybody started getting frantic and then we stopped serving," she said.
"I don't think it should be something that's happening at these types of events."
A large police presence remained around the festival, an annual celebration of Latin American culture that draws thousands of people to Toronto's St Clair West neighbourhood for live music, dancing, food and cultural performances.
"I'm deeply disturbed and angry about this reckless and irresponsible act of violence right in the middle of a festival attended by families," Toronto Mayor Olivia Chow said.
Ontario Premier Doug Ford said in a social media post that his thoughts were with the victims, families and others affected by the shooting.
"I am devastated by the senseless violence at the Salsa on St. Clair Festival that has claimed two lives and injured others," Ford said.
Toronto, Canada's largest city, is among North America's safest major cities. Fatal shootings, particularly those involving multiple victims in public places, are relatively rare.
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