PC Tom Van Der Wee of Sussex Police tweeted this afternoon (January 24) that fire, ambulance and police were in attendance in the westbound lane.
Lane two was closed, causing heavy traffic, said the tweet.
A West Sussex Fire and Rescue Service spokesman said the service was called to a collision between a car and a van at around 4.59pm.
Noone was trapped, said the spokesman, and the fire service was no longer in attendance as of around 5.15pm.
The collision is reported to have occurred at the B2132 Yapton Lane turn off.
South East Coast Ambulance Service have been contacted for more information.