The STM orange line has been shut down between Berri-UQAM and Beaubien stations, according to a series of posts to the ligne orange Twitter account.
The service interruption is due to an injured or ill passenger. There are few other details.
Service was initially supposed to resume at 4:15, but the restoration has been pushed to 4:30.
As of 4:25, service is gradually resuming on the Orange line. It is unclear if a service slowdown will persist into the commuting hours.
Passenger illness is one of the leading causes of metro service interruptions. Last month, the STM launched a public ad campaign (a revival of the much-maligned "conseils de Michèle) to advise passengers on how to avoid behaviours that may cause delays.
UPDATE 5:19: normal mtro service has resumed on the orange line.
We will update this article with more information as it becomes available.