The raids took place Wednesday at dispensaries in Springfield as well as some homes. Authorities said a search warrant for offices of the City of Springfield sought documents about licenses.
Police seized 150 marijuana plants, seven handguns, ammunition and improvised explosive devices.
One of the raided businesses was The Karmacy. Its lawyer, Bruce Leach, said it was operating legally.
Southwest Compassion Care Center co-owner Michael Cain said it was "looted" by police.
Michigan voters in 2008 approved marijuana for some chronic medical conditions, but the Michigan Supreme Court in February slammed the door on marijuana shops.