KENT — The city of Kent has shut down 18 illegal massage businesses that were not in compliance with state health standards.

City authorities say the illicit businesses operated late at night and were often fronts for organized crime, KING-TV reported.

There was a high level of concern that the businesses were part of an international human-trafficking scheme, Kent City Attorney Pat Fitzpatrick said.

Kent Police Department officers began investigating in 2018 and found 18 storefronts that were hubs of illegal activity, authorities said.

A recently passed city ordinance made it easier for police to arrest massage business owners who break the law, police said. The new ordinance allows police to determine whether or not businesses are in compliance with state sanitation and hygiene requirements, city officials said.

None of the businesses that were shut down returned, but authorities are concerned that people associated with those businesses moved elsewhere in the region, officials said.

The department is willing to share what they’ve learned with other departments, Kent Police Chief Rafael Padilla said.