Girl in back seat of SA car roll critical

A young girl is in a critical condition after spending more than an hour trapped in a car that rolled, with two other kids on board, north of Adelaide.

Police say a 30-year-old woman was driving the car with three kids inside when it rolled on Port Wakefield Road in Virginia just after 10am on Friday.

A 12-year-old girl, who was in the back seat of the car, has been taken to the Royal Adelaide Hospital in a critical condition with serious head injuries.

The girl had been trapped in the vehicle for more than an hour after the crash.

The driver and two other kids, a 13-year-old girl and 12-year-old boy, have been taken to the Lyell McEwin Hospital with non-life threatening injuries.

Investigators remain at the scene on Friday afternoon to determine the cause of the crash and part of Port Wakefield Road is closed to northbound traffic.