The incident happened around 5 p.m. on Saturday 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.

There were "nine, maybe 10, victims of varying kinds of injuries," Bouchard said, adding that the victims were of various age groups, with the youngest identified as eight years old, Xinhua news agency reported.

The suspect was "contained" in a house half a mile from the park, Bouchard said.

The police recovered a 9-mm handgun and three magazines at the scene.

The police issued an emergency alert on Saturday evening, warning residents in Rochester Hills of an "active shooter" and urging them to "avoid the area and seek shelter".