Around 60 firefighters are tackling the major blaze on Eastbourne Pier.
East Sussex Fire and Rescue Service confirmed the fire has engulfed a two-storey building on the pier, around 50 metres from the shoreline.
One of Eastbourne's seafront hoteliers tweeted their despair at seeing thick smoke pouring from the 1870s pier:
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Some children, particularly those who have been more directly affected, may show symptoms of stress and trauma.
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The threat level has been raised to critical by MI5's Counter-Terrorism Analysis Centre.