The ambulance service responding to the incident in Strangford Lough has said that some people are suffering from hypothermia, UTV reporter Aidan Kennedy has tweeted:
BREAKING NEWS - AMBULANCE SERVICE SAYS A NUMBER OF PEOPLE WITH HYPOTHERMIA AFTER 100 PEOPLE FEEL INTO WATER DURING KILLYLEAGH BOAT RACE
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The band announced at a free concert on Friday that they would take over the event's Pyramid stage on Saturday June 25.
The victims were collecting permits and escorts a day after their home town was liberated from the extremists.
Scotland Yard said the male youths will appear in custody at Westminster Magistrates' Court on Saturday.