3:45PM: Queensland Ambulance Service have confirmed three males were transported via ambulance to Gladstone hospital with unknown minor injuries.
The QAS also confirmed a 45-year-old female was transported via the Capricornia Rescue Helicopter to Rockhampton Base Hospital with crash concussion and other minor injuries.
Queensland Police have confirmed the Dawson Highway is now open.
1:30PM: QLD Police confirmed the highway would be closed for at least another hour.
A female driver was transported to Rockhampton Base hospital with non-life threatening injuries.
A forensic crash investigation unit is currently present at the scene.
12:52PM: BOTH vehicles involved in the crash near the Calliope range have suffered extensive damage.
A Landcruiser towing a trailer has left the road and rolled, while a smaller vehicle has had its front completely torn off and remains near the road.
What appeared to be gas bottles have been removed from either the Landcruiser or its trailer and fire crews are working to make the area safe.
The Dawson Hwy remains closed due to debris across the road, and it is expected to remain closed for some time.
Traffic is now backed up to the bridge over Running Creek on the eastern side of the range.
12.31PM: FOUR people are being transported to hospital after a serious head-on collision on the Dawson Hwy west of Calliope.
A middle-aged woman is currently being treated at the scene by paramedics for a concussion and some lacerations to her head.
A Queensland Ambulance Service spokesman said she will soon be taken by helicopter to a nearby hospital.
Three males have also been transported to Gladstone Base Hospital by ambulance, one with lacerations to his arm and the others with minor injuries.
EMERGENCY services have now arrived at the scene of a two vehicle collision near Calliope.
A Queensland Police spokesperson was unable to provide a precise location but said the incident took place on Dawson Highway, 45km west of Gladstone.
The highway is blocked in both directions.
Queensland Ambulance reported it was a "head on collision" with "excessive damage" with "the rescue helicopter landing at the scene now".
Initial reports suggested the occupants were able to remove themselves from the vehicles and were being treated for minor injuries.
Emergency services confirmed they were able to render gas cylinders, jerry cans and fire arms in the vehicles secure.
More updates to follow.