Quebec's public security minister says one person is dead and three others are injured after a collision between two small planes over a bustling shopping mall south of Montreal.

Martin Coiteux gave the update while attending an event in Montreal this afternoon.

Earlier, Longueuil police said each plane only had a pilot on board and that both were injured. One of the planes crashed on the roof of the Promenades Saint-Bruno, while the other slammed into the parking lot.

A security perimeter has been set up near the shopping centre. Witnesses at the scene described hearing a loud bang.

Nheil Martinez, who works inside the mall, was outside smoking a cigarette when he says he saw the shadow of a plane and heard its motor.

"I heard the motor so low to the ground and then a loud boom," he said. "Then we saw pieces of plane fall out of the sky everywhere."

Martinez said he ran to the plane and saw a man inside, whose body was crushed.

Jonathan Vanasse was eating inside a mall restaurant next to the crash site. He said he and several others ran outside and saw the plane, which he said was leaking fuel.

"There was just shredded metal," he said, referring to what was left of the aircraft.

On Friday afternoon, the Transportation Safety Board of Canada announced it was deploying a team of investigators to the site. The TSB said in a statement both planes were Cessna 152 aircraft operated by Cargair.

Cargair is a pilot-training academy based in nearby Longueuil. The company did not want to comment when reached by The Canadian Press.

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