Authorities are yet to determine the cause of a gas leak at a Sydney restaurant that has left one person dead and several police officers injured.
Emergency services were called to an Indian restaurant in the north-west suburb of Riverstone on Tuesday morning by the owner of the eatery and his son after finding a 25-year old man unconscious.
Five police officers who came to the scene tried to revive the man, but suspected they were exposed to a substance in the air, NSW Police said.
The officers tried to move the man elsewhere and resume CPR, which was unsuccessful.
"The five police officers involved ... were extremely brave," NSW Police assistant commissioner Gavin Wood told reporters on the scene on Tuesday afternoon.
"They put their lives at risk going into the environment, commencing CPR, trying to save this young man's live and now they are themselves subject to medical intervention."
Wood said the death of the man was a tragedy.
Fire and Rescue NSW said it identified a source of carbon monoxide at "extremely high levels" in the building.
An investigation into the cause of the gas leak is continuing.
