Motorists are reporting seven miles of delays following a crash on the A27.
A car overturned on the eastbound carriageway between Falmer and Lewes.
It is understood other vehicles subsequently struck this car.
Traffic news said: “A couple of vehicles involved, including a car towing a trailer. Queues back past Stanmer Park.”
A Sussex Police spokesman said: "Just before 10.45am car towing a trailer on which there was another vehicle, overturned on the eastbound A27 at Falmer, overturning the trailer at the same time.
"The driver of the towing car is understood to have been slightly hurt.
"The eastbound carrigeway was blocked but it was hoped that it would be cleared about 12.30pm.
"No further relevant information is available on our incident system at this time."
Writing on Twitter, Brighton and Hove City Council said: "A27 pretty much at a standstill eastbound at Falmer. Please avoid if possible."
Did you get stuck in it? Email Anna Roberts.
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