A car carrying six people, including five children, crashed on George Downes Drive in Bucketty, about 50 kilometres south of Cessnock, shortly before 1pm on Monday.

The girl died at the scene.

Careflight said paramedics and the helicopter's doctor worked together to treat four other children. An 11-year-old girl suffered a serious head injury and was flown to Westmead Hospital accompanied by her mother, a woman in her 30s, who police believe was driving the car.

The three other children suffered minor injuries, but the Westpac Rescue Helicopter later flew them to Westmead, Careflight said, so the family could stay together.