Two men are in hospital after being stabbed at London's Wireless music festival, Scotland Yard has said.
The attack happened at approximately 9pm whilst headline acts Justin Timberlake and Jay-Z were performing to tens of thousands of people.
A police spokesman confirmed one man in his 20s is currently in a critical condition and the other man, also believed to be in his 20s, is in a stable condition.
No arrests have been made. Anyone with information is being urged to contact the police.
The festival, held at the Queen Elizabeth park on the Olympic site, came to a close shortly before midnight on Sunday.