Crime scene was declared at Coochin Creek after two people died in the car this morning.
Men and children died inside the car at the Roys Road camping site at about 8 am.
Their bodies have not yet been officially revealed.
At this stage the detectives consider the death of the child to be suspicious and the death of the person to be suspicious.
The investigation continues.
If you have information about the police, please contact Policelink on 131 444 or use the online form to provide information 24 hours a day.
You can call Crime Stoppers, a registered charity and community volunteer organization, at 1800 333 000 or report criminal information anonymously 24 hours a day through crimestoppersqld.com.au.