A man in his 20s was found with stab wounds and despite the efforts of London Ambulance Service officers, he was pronounced dead at the scene.
The Met launched a murder investigation into the fatal stabbing on Thursday morning (February 1).
A post-mortem examination will be arranged in due course and formal identification of the victim awaits.
His next of kin are aware.
Four men, all prisoners at HMP Wormwood Scrubs, have been arrested on suspicion of murder.
Two of the four men are 21, one is 20 and the other is 23.
All four remain in police custody.
Detectives from the Homicide and Major Crime Command are investigating.
Further enquiries into the incident continue.
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