A butane gas canister in the bedroom is believed to have been the cause of the explosion, but investigations were continuing.
"We've taken a number of items as exhibits, including carpet samples to confirm the source of the fire,'' he said. "One of the canisters could have been leaking, but the man could have been doing something else, too, but he was in no condition to sit down and have a chin wag.''
Mr Brown said the problem with LPG was you couldn't necessarily smell it. "But if you light a cigarette you get a contained explosion, especially if the can has been leaking.''
"We've completed the scene examination, but until the man in hospital is able to speak investigations will continue,'' he said.
The Dannevirke Volunteer Fire Brigade were first called to the scene around 1pm and returned later in the afternoon as a precaution.
The second man in the house was stressed, but unhurt.