WATCH: Metro car rides between stations with a set of its doors wide open

Montreal's transit authority is investigating after a pair of videos were posted to Facebook showing a metro car riding between stations with one of its doors wide open.

The videos both show the train — one of the older MR-63 trains which are being phased out as the new Azur cars enter service — travelling westbound on the green line between Pie-IX and Joliette stations from different angles.

They were both posted to the STM: Spotted Facebook page early Tuesday, and quickly went viral.

It appears the video was shot during off-peak hours, with no crowds around.

The STM issued a statement Tuesday afternoon, saying their metro team is analyzing the situation.

According to them, they say the door was closed normally when it arrived at Pie-IX station, and then it opened and stayed open for the ride to the next station on the line, Joliette.

The operator manually closed the door at the Joliette station.

The STM's working theory is some sort of mischief, but they advise passengers that if they see a similar situation, they can pull the emergency brake, and the train will stop at the following station. The train's operator would then be informed of the problem.