Child remains in critical condition after surviving crash into dam

The boy who is still in critical condition was flown to Queensland Children's Hospital after paramedics did CPR, while another child was treated on scene.

The two adults were taken to Princess Alexandra Hospital in stable conditions with leg injuries.

Police divers and the forensic crash unit were on scene.

Police inspector Douglas McDonald said passersby, including two off duty doctors and one critical care paramedic, stopped to help, pulling the family out of the vehicle.

"Their actions were certainly pivotal in making sure this wasn't worse," he told media on Sunday.

Inspector McDonald said the scene was confronting.

“These things are terribly tragic, particularly for the family and friends of those involved, but also for the emergency responders and also those rendering assistance as well – it’s a very tragic and confronting scene," he said.

“The vehicle has collided with the road barriers on one side before crossing onto the other side of the road, colliding with those road barriers and then going into the dam."

QAS senior operations supervisor Mark Nugen also praised the passersby.

"There was a remarkable amount of other people that did support, from the general public, and through that, we were able to get the best outcomes for the patients that we could," he said.