Traffic has built up between Hollingbury and the Amex stadium following a crash at 4.22pm near Falmer.
Police have not confirmed exactly how many cars were involved in the crash but say at least three are thought to be connected with the incident.
AA Live Road Maps show that there are delays of nine minutes and delays increasing on A27 Lewes Road Eastbound between Coldean Lane (Hollingbury / Ditchling junction) and A270 (Stanmer Park).
Due to delays, vehicles are travelling at an estimated speed of ten mph.
