In a tweet posted Friday afternoon, Montreal police say an operation is underway at the intersection of boulevard Saint-Laurent and rue Saint-Viateur.
UPDATE: Police say "no threat" has been identified.
The SPVM asked people to avoid the area.
A report from TVA Nouvelles indicated that a possible hostage situation is ongoing.
TVA also reports that some Ubisoft employees appear to have managed to get onto the roof.
This article will be updated.