Smoke On The STM Orange And Green Metro Lines Forces Second Major Shutdown In Two Days

Sections of both the Green and Orange STM metro lines have been shut down because "of the presence of smoke" according to the STM website.
This is the second major metro disruption in two days. Yesterday, an underground explosion froced officials to shut down the entire Blue line for nearly four hours.
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Shutdown ORANGE line between Snowdon and Bonaventure. Presence of smoke. Service expected to resume at 14:55. #stminfo A
Shutdown GREEN line between Angrignon and McGill. Presence of smoke. Service expected to resume at 15:00. #stminfo Q
While service is expected to resume at 14:55 on the Orange line, the Green line will not be operational until 15:00.
The shutdown affects the eastern wing of the Green line (from Angrignon to McGill stations) and part of the eastern wing of the Orange line (from Snowdon to Bonaventure stations.
UPDATE: as of 15:05 service is resuming on both lines.
Normal métro service #stminfo S
Normal métro service on ORANGE line. #stminfo E
The STM has not divulged the source of the smoke. But the speed with which both lines reopened suggests that this was a minor incident and that they are no safety concerns.
This is a developing story.
This post will be updated with information as it becomes available.