An outdoor party in Toronto turned deadly when gunfire broke out.

FOX News Radio's Steve Rappoport reports:

More than 200 people gathered at the barbecue in the city's east end but the celebration was broken up by bullets and the crowd running for cover.

(Blair) "An altercation broke out among some individuals and there was an exchange of gunfire. During that gunfire, a number of innocent bystanders were struck."

Police Chief Bill Blair.

(Blair) "This is not only unprecedented in Toronto. I have been a cop for 35 years and this is the worst incident of gun violence in my memory anywhere."

Two people were killed and at least 19 injured. Authorities have a person of interest in custody and are searching for other suspects.

Steve Rappoport, FOX News Radio.