An off-duty doctor says a crash that left two toddlers fighting for life on the Sunshine Coast is the most dramatic scene he has ever encountered after he heard the collision and rushed to help.

The sisters, aged one and three, were unconscious when emergency services arrived at the scene of a multi-vehicle collision at Banya near Caloundra yesterday morning.

The girls and their mother were travelling in a blue station wagon when it was struck by an out-of-control truck at an intersection on Banya Avenue.

“They sustained quite significant head injuries, both of them,” paramedic Nick Haug said.

“Their mother wasn’t as critical, however, in a serious condition. We suspected she’d been knocked out because she didn’t have many recalls of the event.”

The crash began when a silver Nissan was sent flying in the first collision, landing against a fence.

But the truck kept going, travelling another half a kilometre before it smashed into the blue station wagon, knocking it into two other cars that were stopped at traffic lights.

Off-duty doctor Marcio Brussius Coelho heard the collision and raced to help, providing first aid to the three-year-old girl until an emergency helicopter arrived.

“Quite, I’d say, emotional as a father and having kids that age as well,” Coelho said while tearing up.

“But at the moment, you just have to do what you need to as a doctor.

“Immediately I thought, this kid needs to go straight to Brisbane.”

The three-year-old was airlifted to Queensland Children’s Hospital, with her younger sister following later.

Both remain in critical condition.

“That was the most dramatic scene I’ve ever seen,” Coelho said.

Police are investigating whether the truck driver suffered a medical episode moments before the crash.

“We have specialists, police investigating the accident. That will be one avenue that will be looked into,” Acting Inspector Matt Robertson said.

The girls’ mother has since been released from hospital, where she now waits and hopes for her little girls to pull through.