Toronto Police Chief Bill Blair told reporters there was "a strong indication there may have been gang involvement" in the Monday night shooting that killed two people and injured 23 others, and warned of the possibility of retaliation.
A 14-year-old girl killed in the gunfight in the city's east end is being described as a top student and avid basketball player.
Friends and neighbours said that Shyanne Charles, the oldest of four children, lived in a townhouse complex a few blocks west of the shooting.
"She was really athletic, she always had a smile on her face. She was generous and joyful and up and about. She never put anyone down," said one 12-year-old girl who knew the victim. "She was really sociable."
The violence came after a neighbourhood barbecue in Scarborough was inundated with strangers. An estimated 200 people were in the area when an altercation led to an exchange of gunfire, sparking panic.
The other fatal victim in the Monday night shooting was identified by a friend as Joshua Yasay, 23, of Ajax. The man asked for privacy and would not comment further.
At a Twitter account in the same name, the last message offered congratulations to a basketball player newly signed to the Toronto Raptors: "You'll love it here! City like no other!"
A 22-month-old infant was among the many wounded but is expected to survive.
The volunteer director of a nearby community youth group said he arrived at the scene shortly after finding out one of the victims was Shyanne. He had known her for a few years and she would sometimes drop in on his programs.
"She was a good person with a bright future," Damon Maraj said. "She had a lot of good friends, that were like her."
Jam Johnson, a youth worker and executive director of the neighbourhood basketball association, remembered her participation in No Books, No Basketball, a homework and sports program. "I see her every day," Mr. Johnson said. "She doesn't pass the street without saying hi to me."
Toronto's Mayor came out strongly in defence of the city's safety in the wake of the shooting, that also injured 23 people and left the city's police chief saying he could remember no worse violence.
"Toronto's the safest city in North America," Mayor Rob Ford said Tuesday morning. "I assure you, Toronto is not like Detroit. People should come here and enjoy this great city."
The Mayor - who described the homicides as "unfortunate, isolated incidents" - toured the site with a pair of detectives, a staffer and a uniformed officer. Afterward, he described it as a place of scattered empty cups, alcohol bottles and shell casings.
A few blocks away, at the complex where Shyanne lived, the kid-filled complex was humming with activity as neighbours greeted each other outside their homes or sat in a few shady spots near an adjacent apartment block. Word of the tragedy spread quickly through the community, many of whose members had been at the barbecue.
"She was a really good girl, she had a lot of friends. She was never in trouble," said Faith Black, 32. "I'm still in denial."
The shooting happened on Toronto Community Housing property and the TCH's president said that both fatal victims were residents of the social housing provider. Gene Jones said that the party hadn't been approved, but should have been. He urged witnesses to speak to police but seemed to understand why they might be scared.
"Let's make this real, they talk to the police, they go and arrest the person," he said. "The problem I've had is that the judicial system will put them back on the street."
Shannon Longshaw said that the barbecue started as an event for her three young children and local kids who live around the Scarborough neighbourhood. She said there was face painting and other activities throughout the day. But strangers started to show up - apparently seeking a party promoted on social media - and around 200 people were there when gunfire broke out. Chaos erupted as people fled.
"Everybody went crazy," Ms. Longshaw said. "Everybody was screaming, looking for their kids. That was the main concern, the children, because it was for the kids."
Police and paramedics swarmed the area. Two people were pronounced dead at the scene.
"By the time I got to the park, they had her in their hands and they put her on the stretcher and started pumping her chest," Ms. Longshaw described Tuesday morning. "I dropped to my knees and started to break. I swear to God. I dropped to my knees and said, 'god, don't let this little girl die. She could be my daughter, please.' That was it."
Ontario Premier Dalton McGuinty spoke to Mayor Ford and Police Chief Bill Blair Tuesday morning to discuss convening a meeting with politicians and others to assess whether more stringent measures are needed to prevent other fatal shootings.
"They are, in a word, outrageous," Mr. McGuinty told reporters on Tuesday. "It is something we cannot and will not stand for."
Gunshots rang out around 10:40 p.m., said police, who believe at least two individuals opened fire. Several witnesses reported that two pregnant woman were among the injured, including one who appeared to have been trampled in the melee.
A handgun was recovered at the scene. One individual whom police called a "person of interest" was injured in the gunfire and taken into custody. Chief Blair said Tuesday the individual remained a person of interest but would say no more. He would not reveal how many rounds had been fired but said that some had hit more than one person.
In the immediate aftermath of the shooting Chief Blair had expressed his shock at what happened.
"This is an area of the city that has never experienced this level of violence before," he told reporters. "Forty-three division is one of the largest divisions in the city, and so far this year they've had six shooting occurrences. In one single evening, to have two people lose their lives, 19 innocent people cut down by gunfire, it's a very shocking incident."
With a report from The Globe and Mail's Stephen Spencer Davis, Matt Robinson and The Canadian Press