Police are appealing for information and witnesses following a stabbing in a bank in Stoke Newington High Street, N16, on Friday, 12 June.
At 10.54am police were called to reports of a male being restrained on the floor in the Hackney street.
Officers and London Ambulance Service attended.
A man, aged in his fifties, was found nearby suffering multiple stab wounds.
Another man, aged in his forties, had been restrained on the floor by members of the public. He was arrested on suspicion of attempted murder; he was first taken to hospital for a minor head injury but later discharged and taken to an east London police station.
A knife was recovered at the scene.
The victim was taken to hospital. Doctors assessed his condition as not life-changing or life-threatening.
Officers are maintaining an open mind about the motive for the attack.
Detective Sergeant James Tipple, from Hackney CID, who investigates, said: “The victim was stabbed in broad daylight as he went about his business. He suffered multiple stab wounds in what was a horrific incident and will undoubtedly stay with him for a long time to come.
“We’re conducting extensive enquiries into this attack and have been gathering evidence. However, I know many people saw this attack and, if anyone has any footage or information about this incident, please come forward and tell us what you know.”
Anyone with information can call 101 and reference CAD 2315/12JUN.