A motorcyclist has suffered life-threatening injuries in a collision on the A23 at Hickstead this afternoon (Sunday, August 18).
Emergency services were called to the scene just after 5.30pm.
An air ambulance landed on the southbound carriageway, which has been closed causing a long tailback.
The northbound carriageway currently remains open, but is very slow.
Police are advising motorists to try and avoid the area for the next few hours while rescue, recovery and investigation work is carried out.
Anyone who witnessed the collision is asked to call Sussex Police on 101 quoting Operation Adder or e-mail email@example.com.