Two men and a woman all from the one family have been found dead in an empty water tank on a property in Gunning in the NSW Southern Tablelands.
The trio were all aged in their 60s, with police investigating if they were overcome by fumes.
It’s understood a man collapsed while working in the empty in-ground cement water tank on property just out of Gunning on Thursday, with a woman and another man going to help but they also collapsed inside the tank.
A neighbour contacted emergency services just after 6pm but all three were found dead, although their deaths are not being treated as suspicious.
Investigators are looking at whether emissions from a petrol engine, possibly a pump in or near the well, contributed to the deaths. A gas detector had found high levels of CO2 in the tank, according to the local paper the Yass Tribune.
Police said post-mortem examinations, to be carried out over the coming days, would help piece together what happened.
Police will address media later on Friday over the accident.