The Toll Air Ambulance has landed at Cataract following a three car crash on Appin Road near the Princes Highway.
NSW Ambulance was called at 7.45am and told Wave FM all three vehicles had single occupants.
A female driver was trapped inside her car for around 45 minutes.
She has been freed and has chest and lower leg injuries.
The medical team from the chopper is assessing her before making a decision whether to transport her to hospital by air or road.
A male driver has suffered minor injuries while another woman was uninjured.
Appin Road is closed in both directions.
Diversions are in place with motorists advised to use Picton Road, the Hume Motorway and Narellan Road.
Image: Travis Winks