Halliday Square remained cordoned off on Tuesday as forensic scientists and detectives from the Homicide and Major Crime Command worked at the scene.
Police were called at around 3.30pm on Monday. Officers found a 26-year-old victim suffering from stab injuries.
An air ambulance landed but the man was pronounced dead at 4.05pm.
Flowers have been left in Halliday Square for the victim, who was known as Rotimi according to the Evening Standard.
The victim's next of kin have been informed and a formal identification process and post-mortem examination will be held in due course, a police spokesman said.
A 39-year-old man was arrested at the scene and remains in custody at a north London police station.
“Police are not looking for anyone else in connection with the investigation at this time,” the police spokesman added.
Anyone with information is asked to call police on 101 quoting CAD 6282/19 Feb, or contact Crimestoppers anonymously on 0800 555 111.
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