The overpass was struck by a dump truck with its box propped up. Eyewitness Alain Collin said the truck was westbound when it hit the overpass.
Longueuil police said they were called to the scene at 7:48 p.m. on Tuesday night.
Collin told Radio-Canada he saw a truck carrying snow, which hit the overpass, knocking it down.
Quebec's provincial police confirm a woman has suffered minor injuries in the collapse.
Highway 132 is closed in both directions.
More to come.