"The back window had already blown out," said Neil Morey, after he had run to the back of the neighbouring property in Cockerell St, Brockville, yesterday afternoon and knocked on the back door and the windows around the side.
His wife, Vishal Morey, called emergency services.
It turned out no-one was inside, and fire crews from Roslyn and Dunedin City, supported by St Kilda and Lookout Point, dealt with the fire quickly.
Fire and Emergency NZ received calls about 3.45pm and the fire was out within an hour.
Roslyn station officer Stuart Slade said the fire was well alight at the back of the property when firefighters arrived.
They gained access through the front of the house and fought it from inside.
The rear of the house was significantly damaged, he said.
Mrs Morey said she had been hosting a family gathering and, when they went outside to farewell their guests, they noticed smoke coming from the neighbouring property.
It was fortunate the group had gone outside when it did, she said.
A fire investigator was at the scene yesterday evening.
Dunedin firefighters also attended a small kitchen fire in David St, Caversham, about 7.30pm.
One person was treated for smoke inhalation.
