One man was fatally stabbed in Stoke Newington, northeast London.
Metropolitan Police watched the scene on Matthias Road at around 5.50 pm tonight, after reports of a stabbing.
Police found a 30-year-old man suffering from stab wounds.
Police performed CPR before an ambulance arrived, but despite their efforts, the victim died on the spot.
A metropolitan police spokesman said: "Police are working to inform their close relatives.
"At this early stage there were no arrests.
"The homicide and major crime command will be reported."
A Section 60, which allows police to stop and search without a reason, is in effect for ZIP codes N16, N1, and E8.
:: Any witnesses or persons with information should call 101 ref CAD 5783 / 17Apr. Alternatively, twitte @MetCC.