Further inquiries indicate it is possible another child, the 12-year-old boy, was a passenger in the vehicle.
At a press conference on Thursday morning, Investigators revealed that a major land and air search is now underway for another child who they believe may have also been in the auto.
Nobbs said police still couldn't rule out the possibility that there had been other passengers in the vehicle when it broke down.
Earlier, police confirmed a man and woman, both aged 19, and a three-year-old boy were found dead about 4.5 kilometres from their broken down vehicle. Authorities initially thought the passengers had died in a vehicle crash but they now suspect the family died of exposure.
"We will continue a precautionary land and air search until we are satisfied that all areas of interest have been sufficiently canvassed", he said in a statement Thursday.
The family were last seen leaving Willowra on Friday and were bound for Yarra Yarra.
"This is a tragic situation and our thoughts remain with the families affected by this incident".
Remnants of food and water were also discovered at the scene.
NT Police were alerted to the deaths, which were not believed to be suspicious, when a person walked into a local health clinic and raised the alarm just after midday yesterday.
"He will be a critical part of the investigation".
"This does serve unfortunately as a timely reminder for anybody traveling on the Northern Territory roads to ensure that, when you do travel, your vehicle is in a fit state to travel". "He's quite distraught about what he's found", he said.
Police are appealing to members within those communities to contact police immediately on 131 444 should they locate or have information on the child's whereabouts.