One lane of the A264 is blocked after a car overturned near Pease Pottage.
Police were called to the incident between the Tollgate Hill roundabout and Horsham Road roundabout at 7.45am, a spokesman confirmed.
One vehicle had overturned, police said.
The ambulance service was on the scene treating a woman for an arm injury, according to police.
Police said one lane is blocked but traffic is flowing.