Hato Hone St John was notified of the incident at 7.47am.
One ambulance and one operations manager responded.
One patient, in a minor condition, was assessed and treated at the scene, with no transport required.
Dunedin Bedding Bank organiser Janine Walker, who worked to establish the encampment, said she had been contacted by a resident earlier this morning who let her know that everyone was safe.
She said a wooden structure, built by one of the homeless residents last month, was at the centre of the blaze.
The homeless encampment at Dunedin's Kensington Oval. Photo / Ben Tomsett
Police confirmed they were assisting Fire and Emergency and were called about 7.45am.
The encampment has been home to fluctuating numbers of people in recent years as the number of homeless people in Dunedin has surged.
Stats NZ estimates put the number of homeless people in the city at 3207, which includes street sleepers, couch surfers, those in temporary housing, and those in uninhabitable homes.
The number of people sleeping outdoors, including in tents, is estimated to be 70-100 at any one time, with up to 60 people possibly at the Oval.