There was a freight train derailment between Laval and Terrebonne over the Mille-Iles River.
The Terrebonne fire department told CJAD 800 News four empty train cars fell into the water, that seven derailed in all.
Some reports said as many as five fell.
It happened near the Sophie-Masson bridge on Montée Masson.
There were no reports of injuries.
An official with the department also said the last car on the train somehow struck the bridge and the cars fell into the water.
A bridge inspection is planned.
He stressed the situation presented no danger for area residents, adding there was no environmental danger either.