Police want anyone who sees groups of suspicious youths congregating to contact them, after a spike in car thefts in the city.
Senior Sergeant Craig Dinnissen said Nissan Tiidas and Mazda Demios had been targeted.
A group of young people may have been behind the thefts, as well as graffiti on several buildings along George St.
Dunedin police have also raised concerns after a fire was lit at Wakari School in recent days.
Snr Sgt Dinnissen said a clump of paper was set alight on a deck at the school, right next to a 100-year old wooden classroom block.
Police had serious concerns about the behaviour, he said.