A man smoking at a pub in east London casually strolled up behind a drinker before repeatedly stabbing him in the back, a video appears to show.
Footage from social media captures the moment that a 23-year-old man was knifed from the blindside amid a crowd of partygoers at the Fatling Pub, in Hornchurch High Street, Havering, on Friday night.
The video shows the victim come into shot holding a cup before a man follows him from behind, cigarette in mouth, and stabs him multiple times.
No arrests have been made and police are appealing for people with information to come forward.
Havering officers from the Met were called to the scene at 12.06am on Saturday.
The victim’s condition is stable, after he received first aid by paramedics and was then taken to a hospital in east London.
Police also released a photo of the alleged attacker, and urged anyone who knows him to get in touch.
Det Sgt Joe Seals said: "We have been carrying out a number of urgent enquiries to track down the person responsible and we are now in a position to release an image of a man we need to identify.
"I would encourage anyone who recognises this man, or any witnesses who have not yet spoken to police, to contact us immediately."
The Fatling pub posted on Facebook: “Sadly last night we had an incident here at the Fatling outside the pub, thankfully due to the speedy actions of the staff members and our medically trained door team the incident was dealt promptly and we are pleased to say the victim is well and recovering.”
People with information can call the police on 101 quoting CAD 36/23Jul.
The independent charity Crimestoppers can be contacted anonymously on 0800 555 111.