BALTIMORE (AP) — Baltimore is suing one of the country’s largest manufacturers of “ghost gun” kits.

Mayor Brandon Scott announced the suit Wednesday, the same day Maryland’s ban on the untraceable weapons went into effect.

News outlets reported that the suit was filed in Baltimore Circuit Court against Nevada-based Polymer80, which sells kits for customers to assemble themselves, and Hanover Armory, an Anne Arundel County gun store.

Polymer80 is based in Dayton, just a few miles east of Carson City.

The lawsuit alleges that Polymer80 intentionally undermines federal and state firearms laws by designing, manufacturing, selling, and providing ghost gun kits and parts to buyers who do not undergo background checks.

No ghost guns were seized in Baltimore until 2018, but last year officials say police recovered 324, 14% of all firearms recovered.