The smell of smoke still hung in the air Thursday, a day after a major fire reduced a more than century-old, abandoned building in Montreal to rubble. The fire broke out early Wednesday morning and was reduced to rubble overnight. The Montreal police arson squad has taken over the investigation. De Lorimier Avenue remains closed between De Maisonneuve Boulevard and Logan Street as excavation crews load enormous metal beams into dump trucks. Specially trained police dogs from the Sûreté du Québec (SQ) were brought in to search the debris, in an effort to confirm the fire did not claim any lives. Montreal police say there is no indication anyone was inside the building when the fire broke out. However, squatters were known to be living there, prompting authorities to deploy the dogs as a precaution. Investigators are also reviewing security camera footage from nearby buildings. Across the street, the head office of the CSN union was forced to close Wednesday. A small number of employees returned to the office Thursday, while others worked from home. “We’re going to change the air filters and there’s going to be a company that is going to come in just to check to be sure that the air is safe, before we can tell everyone that he can come back in,” said David Bergeron-Cyr, vice-president of the CSN. Until recently, the union occupied office space in the building that was destroyed. “It’s kind of sad to see this building fell down, burned and everything,” Bergeron-Cyr said. “It was part of our environment for so many years at the CSN. We hope that nobody got injured.” Asked whether the city has a role to play in securing abandoned buildings and preventing squatters from entering them, the mayor’s office declined to comment until the cause of the fire is known. Police say there is still no reason to believe the fire was criminal, despite the arson squad leading the investigation.