A Montreal Metro train struck an object on the tracks this morning, shutting down part of the orange line and forcing an evacuation of the train cars.

The incident happened shortly before 8 a.m. in a tunnel near the Snowdon station.

No serious injuries were reported.

Police wouldn't confirm what object was, but said it wasn't an act of mischief.

A witness told Radio-Canada a backpack got caught under wheels of the train.

However, the STM later confirmed it was in fact a ladder that was run over and caused the service interruption.

The orange line was closed for an indefinite period between the Lionel-Groulx and Cote-Vertu stations. The blue line was also affected between Snowdon and Parc. Service on the blue line started up again just before 9 a.m. ET. The orange line followed soon after.

Emergency shuttles were dispatched to ferry stranded passengers.