The A27 is blocked due to a collision between a motorcycle and a car.
According to traffic reports, there is very slow traffic due to the accident, which happened in the westbound lane of the A27 between London Road in Patcham and A2038 Devil's Dyke Road.
An eyewitness said both lanes were closed and emergency services were at the scene.
East Sussex Fire and Rescue Service said they were called at 5.40pm to the accident, but no-one was trapped. Crews stayed at the scene to keep it safe.
Fire crews left the scene at around 6.15pm.
The incident is causing major delays for commuters.