Police are closing the A27 to traffic in both directions at Selmeston, near Lewes, while a man and a woman are freed from a car which has crashed into a ditch.
The incident happened at about 1.25pm today (Monday, November 3) near the entrance to Charleston Farmhouse.
Fire, police and ambulance are all on scene. The extent of any injuries is not yet known.
Motorists are urged to avoid the area and seek alternative routes if possible.
Anyone who saw what happened is asked to email email@example.com or phone 101, quoting serial 687 of 3/11.