North Dunedin partygoers throwing bottles at an ambulance has prompted St John to insist the public respect its officers leading in to O Week.
St John was called to a party in Hyde St, between Frederick and Albany Sts, about 11.30pm on Saturday.
St John Otago-Southland district operations manager Pauline Buchanan said an ambulance had to "retreat to a safe distance'' after party-goers threw bottles at the vehicle.
Another ambulance returned shortly after with police and took a 21-year-old male patient to Dunedin Hospital in a serious condition.
The cause was classified as a "fall injury''.