A 23-year-old man is critically ill in hospital after being attacked in Brick Lane, east London.
The assault happened in the early hours of Saturday.
Afterwards the victim was found unconscious in Pitfield Street, Shoreditch.
He was taken to hospital with serious head injuries. His condition is described as critical.
A man who was seen leaving the area where the attack took place and heading south along Brick Lane is described as being black, of Somali appearance, and aged between 20 and 25 years old.
Police in Tower Hamlets are appealing for witnesses.
Detective Sergeant Ian Harkes said: “This would appear to be an unprovoked and vicious attack on a young man who was out enjoying the friendly local atmosphere that Brick Lane normally offers.”
Anyone with information should call police on 020 7275 4546 or Crimestoppers anonymously on 0800 555 111.
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