Traders at Scotland’s largest indoor market were baffled by the large police presence and originally thought there had been a hostage situation.
The former job shop was closed to the public in February 2018 and traders said it had appeared empty ever since.
One shocked market stall owner told the Scottish Sun: “There was no warning, they swooped in with a battering ram and caused a bit of a scene.
“Then the police left and started to try and bash in the doors to gain entry to the building.”
It’s understood the culprits forced their way in to the Job Centre after bashing their way through the wall of an empty tanning shop in a neighbouring unit of the Norman House building.
A shocked market stall owner said: “Originally people thought there was a siege or somebody had been hurt.
“They’ve not managed to get in to see the damage caused, they need somebody to come in and open the doors for them.”
Another trader said: “It’s hard to imagine somebody has been growing cannabis so close to the Forge.