AMT commuter trains on the Deux-Montagnes line were cancelled Tuesday during the afternoon rush hour after a 17-year-old girl was hit by a train at Roxboro-Pierrefonds station.
The teen was taken to hospital with life-threatening injuries.
Montreal police said the girl suffered multiple injuries to her head and lower body.
Police spokesperson Daniel Lacoursière said the girl was trying to cross the tracks to catch an eastbound train around 5 p.m. when the incident occurred.
"She didn't see the westbound train that was coming and, unfortunately, she got grazed by the train and fell between the [platform] and the train," he said.
The girl, who police said was wearing headphones at the time, was dragged about 15 metres.
Trains on the Deux-Montagnes line were cancelled after the incident and buses were brought in to get commuters to their destinations.
Train service gradually resumed around 7:30 p.m.