The Princes Highway is closed in both directions at Twelve Mile Peg, north of Conjola, due to a two car crash.
Motorists are advised to avoid the area as there are no suitable diversions available.
Emergency services are working to free a person trapped in one of the vehicles.
Traffic crews are also responding, along with a medical helicopter.
Traffic in the area is heavy. Motorists are advised to follow the directions of emergency services on site.
For the latest traffic information, download the Live Traffic NSW app, visit www.livetraffic.com or call 132 701.