A man is being treated for burns after a gas explosion at a construction site in Zetland in inner Sydney.
The man, aged in 20s, suffered second and third degree burns to 60 per cent of his body after the explosion on Saturday afternoon.
Fire and Rescue NSW Inspector Steve Moran said the force of the blast shattered windows and caused structural damage to the building on Defries Avenue. The injured man was on the seventh floor at the time, he said.
No other people were hurt.
"He's very lucky to be alive," Inspector Moran said.
Police said the man was working on the construction site when the blast occured about 1.10pm.
It's not yet known what caused the gas explosion but Work Cover confirmed it is investigating the incident.
The man was taken to St Vincent's Hospital in a serious condition.
He has since been transfered to a burns unit at Royal North Shore Hospital and is in a stable condition.
