BRISTOL, Conn. (AP) — Police say as many as 40 people were taken to area hospitals after they were exposed to carbon monoxide at a call center in Bristol.

Emergency crews were dispatched to the Faneuil Call Center on Valley Street around 11 a.m. Thursday following reports of the exposure. The building, a former industrial space currently under renovation, was evacuated.

Authorities estimate roughly 30 to 40 people were overcome by the gas, although none of their illnesses appeared to be serious.

Police say a preliminary investigation suggests that a construction company working on the building may be responsible for the incident. Contractors were reportedly using a propane-powered saw to make repairs.

Firefighters removed the carbon dioxide from the building by about 3 p.m.