''One male from the car punched a student in the back of the head and he had to be taken to Dunedin Hospital.''
Snr Sgt Dinnissen said it was not known exactly how many people were assaulted by the group, but he believed ''multiple people'' were attacked in the spree.
''We're looking for reports from those people.
''If they were assaulted as well, we want them to step forward so we can get more information on these people and hold them to account.''
He said a 19-year-old man was arrested for disorder and resisting police, and was given a formal warning.
Another 19-year-old man was arrested for assault and he too was given a formal warning.
A third 19-year-old man was arrested for assault and will appear in the Dunedin District Court on Thursday.
He said the 19-year-olds were not students, and it was unclear what their motives were for the attacks.