The incident happened around 5 p.m. (2100 GMT) when a "random" gunman got out of a vehicle and unloaded 28 gunshots from a handgun, Oakland County Sheriff Michael Bouchard said at a news conference Saturday evening, Xinhua reported.
There were "nine, maybe 10, victims of varying kinds of injuries," Bouchard said, adding that the victims were of various ages, with the youngest identified as eight years old.
The suspect was "contained" in a house half mile from the park, Bouchard said. The police recovered a 9-millimeter handgun and three magazines at the scene.
The police issued an emergency alert Saturday evening, warning residents in Rochester Hills of an "active shooter" and urging them to "avoid area and seek shelter."