Greerton Fire Service station officer Peter Clark, who attended the blaze, said the accident was not the first time someone had been burned after being foolish with flammable liquids.
"People do some stupid things. We've seen it before and it won't be the last time it happens."
Mr Clark warned people to be more careful when working with highly flammable substances.
"Use common sense. Don't smoke anywhere near petrol or any flammable liquids. Keep flammable liquids in an isolated place in a garden shed. Don't have them in the house."
ACC statistics show more than 3450 people made claims for accidents involving fire, explosions and blasts in the last financial year, costing taxpayers almost $10 million.
Auckland plastic and reconstructive surgeon Zac Moaveni said he had treated a South Auckland man just after Christmas who suffered bad facial burns when he lit a cigarette while siphoning petrol from a car at night. "It's just common sense. You shouldn't smoke a cigarette while you're siphoning petrol."
The man, in his 20s, needed surgery and skin grafts.
In another similar accident, Mr Moaveni said a Thames farmer in his 50s was trying to burn out a wasp nest in the ground when the petrol he was pouring in exploded as he lit it. "Unfortunately there was a massive flashback of the flames and his clothes caught on fire."
The farmer suffered serious burns to 30 per cent of his body. Burns to more than 50 per cent of the body were often fatal, Mr Moaveni said.
"Unfortunately [these types of burns are] far more common than you'd expect. A lot of accidental burns are just the result of a moment's not thinking, just a quick mistake and they end up like this."
The man was treated at Middlemore Hospital's burns unit.