According to the STM website, the orange line has been shut down between Berri-UQAM and Henri-Bourassa stations "due to an intervention by emergency medical services."
The STM predicts that service will not resume until 2:00 PM, totalling about an hour of interrupted service.
There are no further details as to the nature of the emergency medical situation.
UPDATE: the STM is advising passengers to seek alternative routes.
The STM has also established a shuttle that is running along the affected orange line route.
UPDATE: normal metro service has resumed.
Stay tuned for updates on this developing story.