Eight people, including six children, injured in van rollover on Hume Hwy

Passing motorists have managed to free eight people, including six children, who became trapped when their minivan rolled on the Hume Hwy in southern NSW.

The van driver, a man believed to be in his 50s, and seven family passengers were freed by other motorists who stopped at the scene in Marulan near Goulburn to help just after midday on Tuesday.

WATCH THE VIDEO ABOVE: Six children injured in Hume Hwy crash.

“We jumped out and went over and noticed there was a girl trapped under the van,” one witness told 7NEWS.

“We pushed the van up and flipped it back over and pulled her out.”

Traffic on the major highway at Marulan was brought to a standstill as three NSW Ambulance helicopters landed on the road and an army of paramedics treated two adults and the children — some with critical injuries.

It is believed at least one of the children has special needs.

The driver was flown to Liverpool Hospital in a critical condition with shoulder and chest injuries, while 7NEWS.com.au understands a woman in her 30s was also in a critical condition with crush injuries to her leg and pelvis and was taken to Canberra Hospital.

Three of the six children were also seriously injured.

One of those was a teenaged girl who suffered crush injuries and was flown to The Children’s Hospital at Westmead in a stable condition.

A boy in his teens was taken to Canberra Hospital in a serious but stable condition.

Three primary school-aged children were also taken to The Children’s Hospital at Westmead with various injuries, with all three reported to be in a stable condition.

It is understood another a girl aged in her teens was taken to Liverpool Hospital for observation.

Hours after the crash the highway was reopened in both directions and “traffic conditions are back to normal”.

Police are now investigating what caused the van to roll.

The driver will undergo mandatory testing in hospital.