Two teenagers remain in Dunedin Hospital with serious burns, after the gas bottle they are suspected of sniffing from exploded.
A fire spokesperson said the 17 and 18-year-old men were inhaling the contents of a 9kg LPG bottle at a house in Mosgiel when the bottle combusted, engulfing the pair in flames.
The teenagers are both currently in a serious condition in intensive care.
One of the men has burns to his internal airways and lungs.
The force of the explosion blew off much of the tiled roof, displaced walls and shattered windows.
"It's incredibly stupid, incredibly dangerous and they were lucky that more people weren't injured as a result," a fire spokesperson said.