The Forensic Crash Unit is investigating a serious two-vehicle crash at Aldershot, north of Maryborough, on October 24.
Initial information indicates a grey Suzuki Swift was travelling northbound on the Bruce Highway about 5.40pm, when it crashed with a prime mover travelling the opposite direction.
The impact subsequently caused the truck to catch fire.
All four people inside the Suzuki were taken to hospital, including a 28-year-old male passenger with life threatening injuries.
The 25-year-old female driver sustained serious but non-life-threatening injuries and two children sustained non-life-threatening injuries.
A 48-year-old male driver of the truck received minor injuries in the crash.
The highway was closed in both directions, with diversion put in place, while investigations were carried out into the cause of the crash.
It has since been reopened.
Anyone who has any information that can assist with investigations is urged to contact police.
If you have information for police, contact Policelink by providing information using the online suspicious activity form 24hrs per day at www.police.qld.gov.au/reporting.
Report crime information anonymously via Crime Stoppers. Call 1800 333 000 or report online at www.crimestoppersqld.com.au.