In what appears to be a series of tragic events, three elderly people have been found dead in a water tank in state's Southern Tablelands last night.
The bodies of two men and a woman, all aged in their 60s, were discovered in an empty ground cement tank on a remote property at Gunning, located between Goulburn and Yass.
Emergency services were called about 6.20pm last night with reports a man had collapsed inside the tank. Another man and a woman climbed down into to the tank to try and get the man out but they also collapsed.
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 has found high levels of CO2 in the tank.
Police said post-mortem examinations, to be carried out over the coming days, would help piece together what happened.
ABC News reported the three people were all from the same family.
Police said a 69-year-old man was working inside the empty cement tank on his property in Gunning, near Yass, when he collapsed.
Another man, aged 68, and a 63-year-old woman jumped into the tank to try to help and also collapsed.
A neighbour who heard the woman call out contacted emergency services, who arrived to find the bodies of all three people.
Emergency services personnel retrieved the bodies from the tank just after 9pm, the Yass Tribune reports.
Police are not treated the death as suspicious.
The names of the deceased have not been released.
Police will address media later this morning.
A report on the deaths will now be prepared for the coroner.