Michigan Department of Licensing and Regulatory Affairs spokesman Jason Moon says inspectors found the bodies Friday at the Cantrell Funeral Home on the city's east side.
Detroit police say eight or nine bodies were found in a cardboard box and the others in one or more caskets, all hidden in a ceiling. Police ordered a search of the building to ensure there are no additional bodies inside.
The regulatory agency suspended the license of the funeral home in April after inspectors found decomposing embalmed bodies and other violations. Violations also included two improperly stored bodies covered in what appeared to be mold and a third body with unknown fluids covering the facial area.