Emergency services were called to the Great Western Highway near Explorers Road at Katoomba just after 6.30am after receiving reports the car collided with a truck.
It’s understood a passerby pulled the girl along with another woman from the burning car before paramedics arrived.
A NSW Ambulance spokesperson confirmed a woman in her 30s was taken to Westmead Hospital in a stable condition.
She was treated for minor burns to the chest and leg.
The girl who is under the age of 10, was airlifted to the Sydney Children’s Hospital in a serious condition.
A third person, a woman in her 40s, was taken to hospital with minor burns.
The woman is understood to be a bystander who assisted in the rescue.
Drivers have been warned to expect significant delays in the area, as the highway remains closed in both directions near Explorers Road.