A police spokesman said one patient died at the scene and three others were injured when two vehicles collided southbound at Figtree about 7.15pm on Friday.
According to NSW Ambulance, a teenager was airlifted to Westmead Children’s Hospital in a critical condition, while paramedics rushed two children to Wollongong Hospital.
The two children were both later taken to Westmead Children’s Hospital in a critical condition.
“No words can describe the scene that we were faced (with) this evening,” NSW Ambulance acting inspector Nathan O’Brien said in a statement.
“Going to a road accident when we know there are children involved is always difficult for first responders.
“Multiple patients with serious injuries can create a very challenging environment for paramedic crews. It is our responsibility to do everything we can to provide life-saving treatment.”
A police spokesman told 9News.com.au the critically injured person had been sitting in the front passenger seat with the youngest passengers in the back.
While the driver of the other vehicle was visibly unharmed, they were also taken to hospital for mandatory testing, the spokesman said.
Earlier reports had indicated as many as five cars were involved in the smash.
A NSW Ambulance spokeswoman told 9News.com.au 12 ambulance crews and two helicopters were called to the scene and treated four patients.
The police spokesman said diversions were in place and crash unit investigators were on the way to the scene.