Detectives are investigating a double stabbing at the Yahoo! Wireless Festival in the Queen Elizabeth Olympic Park yesterday evening.
Two men were taken to separate east London hospitals after suffering stab wounds in the incident at around 9pm, while headline acts Justin Timberlake and Jay-Z performed on stage.
One victim, who is in his 20s, is said to be in a stable condition.
The other victim, who is also believed to be in his 20s, has since been discharged.
It is understood the victims were with a group which became involved in a brawl with up to 10 other men near the front of the stage shortly before the attack took place.
Officers are working closely with the event organisers to investigate the case.
Anyone with information that may assist the investigation should call Newham CID on 0208 217 5851 or Crimestoppers on 0800 555 111.
This is the first year the festival has taken place at the Olympic Park following its relocation from Hyde Park in central London.
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