(CNN) Two people were killed Wednesday in a massive car pileup that shut down a major highway just outside Montreal, according to Quebec police.

The accident involved more than 200 cars, according to CNN affiliate TVA. About 100 people were taken to three local hospitals, according to the CETAM ambulance service. At least nine people were seriously injured and 13 had light injuries, CETAM said.

The two people who died were found trapped in their vehicle, Quebec's public safety agency said. The victims are in the process of being identified, the agency said.

The crash was caused by a "strong" snow squall coming from the St. Lawrence River that "suddenly" generated a total lack of visibility for drivers, Quebec Transport Minister François Bonnardel said during a press conference.

A snow squall is basically a short but ferocious burst of heavy snow and strong wind, usually lasting less than an hour, according to the National Weather Service.

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