Sûreté du Québec raided a Terrebonne business accused of counterfeiting money.
The Economic Crimes Investigation Division dismantled a counterfeit manufacturing laboratory operated out of a store front on Chemin des Anglais in Terrebonne.
On Tuesday, Police seized close to $500,000 of counterfeit Canadian and American notes, as well as tools used to counterfeit.
The counterfeiters were allegedly producing $50 and $100 bank notes.
Three men and one woman were arrested and questioned.
The investigation was launched last November, and was conducted in collaboration with the Royal Canadian Mounted Police.