The bodies of four people were found near a broken down vehicle in the remote Australian outback.
Police say two adults, both 19, and their three-year-old son were found dead near a road about 1,000km (620 miles) south of Darwin and 70km from the Willowra on Wednesday.
A boy, 12, is said to be missing and a body – yet to be formally identified – was found 120 metres from the family.
The deaths are not being treated as suspicious by Northern Territory Police and authorities are investigating whether heat may have contributed to the tragedy.
The group was last seen leaving Willowra, a small community, on Friday. The three bodies were found about 4.5km from the vehicle.
Superintendent Shaun Gill told ABC: “One of the avenues we are looking at is that they have walked off from a vehicle in extreme weather and may have got caught out.
“Initially we thought it was the result of a car crash, however we are confident it’s not.”
Police said the alarm had been raised by a man who entered a health clinic in Willowra on Wednesday.
“He will be a critical part of the investigation. He is quite distraught about what he has found,” said Supt Jody Nobbs.
The officer did not offer any more details or confirm if the missing 12-year-old was related to the family.
Family members have not authorised the release of the boy’s name but say people living in the surrounding communities of Ali Curung, Ti Tree and Willowra are aware of his identity.
Temperatures in the region exceeded 40C in recent days, according to Australia’s Bureau of Meteorology.
The tragedy follows the suspected heat-related deaths of two people in separate incidents in northern Australia within the last two weeks, the ABC reported.