"The kids kept coming out and then we saw the smoke ... it wasn't very nice at all. They have quite a few domestics in there but this is the worst they have ever had.''
Police have not yet released any more details on how the couple suffered their burn injuries.
Private security guards were protecting the scene at the Buckingham St property, which features a three-metre steel gate on its driveway.
Police, ESR forensic and New Zealand Fire Safety staff are all conducting investigations.
Items of interest have been seized from the scene to help work out what happened.
A neighbour who rang emergency services was taken to hospital yesterday. A relative said it was because of the upset of the Christmas fire.
"I think it got a bit too much for her because she has heart problems. She is very stressed-out at the moment.''