A car collision at the Holmbush Roundabout in Shoreham has blocked Upper Shoreham Road.
According to traffic reports, the accident happened by the Southwick exit of the roundabout, which connects to the A270.
It is affecting all approaches to the roundabout.
An eyewitness saw a car smashed and facing the wrong direction, with police and paramedics nearby.
The accident is causing delays in all directions.
The ambulance service said: "At 14.58 we sent an ambulance to a road traffic collision between two cars on the Upper Shoreham Road, Shoreham. A woman was taken to Worthing Hospital with minor injuries.