Police were called at 12.48am on Wednesday, 20 October to Mile End Road, E8 following reports of a man seen in possession of a knife on board a Route N25 bus.
Officers attended and found a 34-year-old man [Victim 1] suffering from stab injuries. They immediately provided first aid.
The man was taken by the London Ambulance Service to an east London hospital where he remains in a critical condition.
Two other men – aged 34 and 22 – were also taken to hospital for treatment to slash injuries; their injuries are not believed to be life-threatening.
A 34-year-old man was arrested at the scene on suspicion of causing grievous bodily harm. He was taken to an east London police station where he remains in custody.
A crime scene remains in place. Enquiries continue.
Anyone with information is asked to call police via 101 quoting reference Cad 244/20Oct. To remain anonymous, contact Crimestoppers on 0800 555 111.