A scene guard was in place this morning at the intersection of Highgate and Hereford St.
A St John spokeswoman said it was called to the property at 2.49am yesterday and one patient was taken to Dunedin Hospital in a serious condition.
The ODT understands the victim was a young girl.
Police tape could be seen at the back of a residential address where an officer was wearing blue forensic overalls and appeared to be using electronic equipment to map the area.
Yesterday about 3pm, a police photographer was taking pictures of the playground on Falcon St and also appeared to be photographing a drain across the road.
About 5.45pm there was a police trailer at the scene and the focus of investigators seemed to be on the backyard of the house.
A police spokesman said a scene examination was happening in relation to a family harm incident.
It is understood that the incident happened in the early hours of Tuesday.
