Two women received minor shotgun pellet injuries while walking along a track beside the Clutha River in Alexandra on Sunday morning.
Detective Sergeant Paul Slater of Queenstown police said the incident happened about 11am.
"The men responsible spoke to the injured women when they realised what had happened and offered assistance, however they left the scene in their boat and have not yet been identified."
Police were notified after the women arrived at Alexandra Medical Centre, where they were treated for minor pellet injuries to the shoulder and lower leg.
The group of men were believed to be shooting from a boat in the river.