Three people have died, including a teenager, and another girl is fighting for life after a head-on crash in southern NSW.

Emergency services rushed to Kings Highway in Monga, an hour south-east of Queanbeyan, after two Hyundai hatchbacks collided head-on.

The female driver and two passengers in one of the cars, a teenage girl and a man, died at the scene.

A teenager is still fighting for life, while three people travelling in the other car were taken to hospital.A teenager is still fighting for life, while three people travelling in the other car were taken to hospital. (Nine)

A teenage girl was airlifted to Canberra Hospital with critical injuries, and is fighting for life.

The driver of the other car, a 31-year-old man, was airlifted to Westmead Hospital in Sydney with serious injuries, while a seven-year-old child in the car was taken to Westmead Children’s Hospital in a stable condition.

A three-year-old child was taken to Canberra Hospital as a precaution.

NSW Premier Chris Minns said today he was saddened by the tragic crash.

“It’s devastating,” he said.

“For the families who have been affected on that stretch of road [we share] our deepest sympathies.”

The highway remains closed east of Braidwood in both directions near Tudor Valley Road, and at Clyde Mountain Road.

Police urged drivers to avoid the area.

A crime scene has been established.