A major NSW highway has been closed entirely in one direction following multiple car crashes.
A two-vehicle crash on the Hume Hwy at Mittagong closed one southbound lane about 11.15am on Monday.
While this crash was being cleared by emergency services, a second three-vehicle crash occurred about 45 minutes after the initial crash.
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A heavy vehicle and hatchback crashed, with the hatchback then rear-ending a station wagon.
A 69-year-old female passenger in the hatchback was trapped inside the vehicle for some time.
The Cootamundra woman was eventually released from the car and airlifted to Liverpool Hospital.
She suffered multiple injuries, including fractures.
The 69-year-old male driver was also taken to Liverpool Hospital, where he is being treated for cuts.
The Cootamundra man will also undergo mandatory testing.
The man behind the wheel of the truck was not injured.
He was arrested and taken to Bowral Hospital for mandatory testing, before being taken to Southern Highlands Police Station.
The couple inside the station wagon, both aged 68, were not injured. The man driving the vehicle has undergone mandatory testing.
No injuries were reported from the initial crash.
All southbound lanes on the Hume Hwy are currently closed.
Traffic is being diverted via the Old Hume Hwy.
Motorists are advised to allow extra traffic time for their trip.