A serious accident involving a lorry has closed part of the A27.
The incident was reported to have taken place at around 2.15pm.
Unconfirmed reports suggested a skip has fallen off the back of a lorry, causing the accident.
An ambulance is reported to have attended the scene.
The road is closed in both directions between Chichester (the Fishbourne roundabout) and Emsworth.
A Sussex Police spokeswoman urged motorists are advised to avoid the area if possible.
A West Sussex Fire and Rescue Service spokeswoman said a crew from Chichester and a fire officer had been sent to the scene supported by a crew from Havant, who had since been stood down.