A police officer was assaulted and another man suffered a serious head injury during the incident at the Melville Hall boarding house in Melville St.
Officers were called to the address following reports of disorder just before 5pm yesterday, a police spokeswoman said.
Two patrol cars were seen outside the address and shortly after the second car arrived, a shirtless man with his hands cuffed behind his back was led from the house by two officers.
"A police officer was assaulted at the scene and has received a cut to the head, but has since been discharged from hospital," the spokeswoman said about 9pm.
"One other person has been assaulted and has suffered a serious head injury and is currently still in hospital, while another person is helping police with inquiries at the Dunedin Central Police Station."
Both the injured man and the man at Dunedin Central were arrested, though no charges were laid as of last night.
It was not the first time the boarding house had come to police attention. A 38-year-old man leapt out of a second-storey window to escape an assault at the hands of a 28-year-old man in January last year. The victim suffered a fractured skull, bruising to the brain, a broken eye socket and three fractured ribs as a result of the fall and assault, and remained in Dunedin Hospital for three weeks recovering from the incident.
