One of the planes crashed into the roof of the mall, on the outskirts of the city of Montreal.
Three others were injured in the accident on Friday, which took place over the Promenades Saint-Bruno.
Witnesses described hearing a loud bang.
According to aviation expert Keith Mackey, a number of things could have caused the crash, including glare from the sun, a possible mechanical issue or the experience level of the pilots.
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Rene Thibault said he was in another of the mall's parking lots when he heard a loud cracking sound.
Martinez said he ran to the plane and saw a man inside, whose body was crushed. One witness said she was anxious one of the planes was going to crash in front of the building's doors but it ended up on the roof instead. The centre was shut following the incident and will remain closed on Saturday.
The Transportation Safety Board of Canada has sent a team of investigators to the site.
Longueuil police will lead the investigation, working with experts from the TSB and Transport Canada to determine exactly what happened.
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The two planes were heading for Saint-Hubert airport - where the Cargair flight school is also based - less than 400 meters as the crow flies from the shopping centre.
"We are concentrating our efforts to help our employees and students who are all part of the Cargair family", said Josée Prud'homme, the company's president.
One eyewitness, Carol Pelchat, told the news channel that she heard two planes overhead when she came out of the shopping mall. A report into the crash concludes the converging position of the two planes would have made it hard for either to see the oncoming aircraft until it was too late.
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