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 family of a 20-year-old man who was stabbed to death have described him as a friendly and happy person who was always willing to help.
Police are asking for the public's help finding a driver who injured a four-year-old boy in a hit-and-run.
The organiser of a Pokemon Go meet-up in central London said he was amazed when suddenly thousands of people said they were going.