MORE lives could have been lost in Monday's horrific crash at Tiaro, if not for the efforts of a doctor and police officers who came to the rescue of a teenager and two others left seriously injured after the collision.

Acting Inspector Paul Algie said a female doctor provided immediate assistance to a 14-year-old boy who was left critically injured after the crash that claimed the lives of his mother and uncle, while the two police officers dragged two others clear of petrol around the cars, which quickly ignited in flames.

"We were very, very fortunate that there was a doctor travelling north very close to where the accident occurred. That doctor was able to provide life-saving support.

"We were also extremely fortunate that the police that attended in Tiaro were only two kilometres away from the accident scene.

"I've been told that the officers arrived there very soon after the accident occurred and were able to drag the driver and passenger of the first vehicle from the petrol that was on the road and dragged them just in time as that petrol took alight. I believe that their actions saved those two people's lives."

Act Insp Algie described the doctor's actions as "fantastic".

"People launch into action and do what they can under very trying circumstances and in horrible, trying circumstances we see the very best in human nature."

Act Insp Algie said at this stage it appeared the first car had veered onto the wrong side of the road while it was travelling in an overtaking lane.

The vehicle then clipped a second vehicle and collided with a third vehicle.

A 30-year-old woman and her 22-year-old brother, both from Brisbane, were killed instantly in the crash.

The woman's 14-year-old son was airlifted from the scene and remains on life support in a Brisbane hospital.

A fourth passenger in the car sustained serious internal injuries and was also airlifted to the Royal Brisbane and Women's Hospital, while the people in the second car escaped unscathed, Act Insp Algie said.

He described the crash scene as being one of the worst he had attended in his 17 years of service.

"It was certainly horrendous, it was very difficult for the emergency services that attended the scene."

Act Insp Algie said the forensic crash unit was still investigating the incident and no charges had yet been laid.

"It was a terrible way to end the Easter long weekend period. All I would say is whether it is the Easter long weekend, or any time, I just urge drivers to drive to the conditions.

"When it's busy on the roads it's so, so easy for things to go wrong."

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