One person has now been released from hospital after being stabbed at the Wireless music festival in east London.
Two people were attacked during the event this weekend.
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The twins cubs, which were born in June, have been named Bert and Ernie after characters from Sesame Street.
The two victims died from their injuries in hospital after the explosion in Hertfordshire.
Investigations are continuing into the cause of the crash in chigwell which killed both people on board.