Quebec police carried out a major raid in the Montreal area early Tuesday, arresting 17 people as part of an ongoing probe into allegations of gangsterism and tax fraud in the construction industry.

Fifty officers raided several homes and businesses in Montreal, the North Shore and Shawinigan.

Surete du Quebec officer Gregory Gomez confirmed 17 people were arrested, saying they will be formally charged over the next two days with taking part in a scheme that allegedly bilked the province out of $9 million in tax revenue. Those arrested are also accused of committing fraud through false billing on construction contracts.

According to a police statement, those arrested face charges that include: theft over $5,000; forgery; uttering forged documents; fraud over $5,000; gangsterism; conspiracy; and living off the proceeds of crime.

Revenu Quebec first alerted police to fraud suspicions in 2010. In 2011, investigators launched Operation Tourniquet, which led to raids on homes and warehouses north of Montreal and, in turn, Tuesday's arrests.

Police say all 17 arrested are involved in the construction industry.

The arrests come as Quebec is in the middle of a major inquiry investigating corruption in the province’s construction industry. The Charbonneau Commission is currently examining whether municipal officials were paid off to slip privileged information to construction companies competing for public contracts, though Tuesday’s arrests are unrelated to that inquiry.