Nearly Two-Dozen People Shot in Toronto

July 17, 2012 Updated Jul 17, 2012 at 8:07 AM EDT

By WKBW News

July 17, 2012 Updated Jul 17, 2012 at 8:07 AM EDT

Toronto, CA (WKBW) - Police officers who have been on the force for decades, said this is the worst tragedy they have ever witnessed This all happened at a block party on the city's East end.

More 200 people were taking part in the celebration when the gunfire started. Police believe it may have started with an argument between some individuals when shots were fired. During the gunfire, several innocent bystanders were struck. The two killed were a teenage girl and a man in his 20's. The other 19 who were injured were either shot or hurt after the mass panic that ensued.

"It's difficult to describe. This is not only unprecedented in Toronto, I've been a cop for 35 years and this is the worst incident of gun violence in my memory anywhere in North America. It's a very shocking event. A lot of innocent people were injured. It appears to have been a dispute and again this is quite preliminary and we have on scene our homicide squad, which is taking over the investigation, but also members of our guns and gangs unit are here, our intelligence unit, the ETF is working side-by-side with them as well as officers from 43 division," Toronto Police Chief Bill Blair said.

Police said they have at least on person of interest in custody and are also interview several other witnesses to see who is responsible for this tragedy. This is being called the most serious crime of its kind that has ever taken place in the city of Toronto.