Police were called to Eastbourne Pier around 4.10pm to a man who had fallen onto the beach.
Ambulance was called and the man was being treated for a serious head injury and he was flown to hospital in a life threatening condition.
The Health and Safety Executive has been informed as the man was working on the pier.
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Monday evening's weather for the east of the region
Monday evening's weather for the west of the region
Monday's lunchtime weather for the east of the region