Dozens of people have been taken hostage at a building containing video game company Ubisoft, foreign media reports.
Employees are said to be hiding under tables in a conference room at the office on Saint-Laurent Boulevard in Montreal, Canada.
A police operation is now under way, with armed officers surrounding the building.
The incident began on the fourth floor of the building around 1.30pm local time.
Dozens of people have been recorded standing on the roof, and a ransom demand has reportedly been made.
One eyewitness tweeted: “Saw cops with guns drawn as people came out of a Ubisoft building with their hands up.”
Several ambulances are standing by to provide treatment.
Sharing a grab of a local news report, Ubisoft employee Eric Pope tweeted: “This is insane. this is my team on the roof.”
One woman told TVA Nouvelles that her partner is trapped inside the building.
She said: “I can’t reach him…I am worried seriously worried.”
No injuries have yet been reported.
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