TORONTO » An exchange of gunfire at a crowded outdoor party in Toronto killed two people late Monday and 22 others, including an infant, were injured by bullets and by trampling in the rush to flee.

"It is the most serious crime of its kind that has ever taken place in the city of Toronto," said Police Chief Bill Blair.

Bullets from more than one gun sprayed into the crowd of more than 200 people, causing a panic.

Police said 19 people appeared to be wounded by gunfire, and three others were trampled.

Police said they had one "person of interest" in custody and were looking for other suspects.

The shooting took place before 11 p.m. at an outdoor barbecue.

"An altercation broke out among some individuals, and there was an exchange of gunfire. During that gunfire, a number of innocent bystanders were struck," Blair said. "It’s a very shocking event."

The two killed were a teenage girl and a man in his 20s, officials said.

Blair said the injuries to the infant are "not life-threatening, and the child will be fine."

Those hurt suffered a mix of gunshot wounds and injuries from the crush that ensued.

The shooting came just weeks after a gunman opened fire in a crowded food court at Toronto’s Eaton Centre mall. One man was killed instantly, another died of his injuries days later and several bystanders were sent to the hospital.