A man was stabbed to death in a fight outside a block of east London flats in a "particularly vicious attack".
The 19-year-old was found by police responding to reports of a disturbance outside Owen Waters House, in Fullwell Avenue, Ilford, on Tuesday night.
The victim died at the scene and his next of kin have been informed.
No arrests have been made but the Met said "the possibility that the murder is gang-related is a very strong line of inquiry".
Police are establishing if the stabbing is linked to a fire at some nearby garages where a car was found burnt out.
The Met said fire crews had been called to the blaze at about 22:20 GMT while traces of blood had also been found around the vehicle.
Det Ch Insp Chris Soole described the killing as a "particularly vicious attack" and appealed for witnesses.
A Section 60 Order - giving police stop-and-search powers - was put in place for the whole of the Redbridge borough until 06:30.
There have been five murder investigations in the borough in 2019 - three of which have been as a result of fatal stabbings.
So far this year, almost 130 murder investigations have been launched in the capital.
Three investigations have been carried out by British Transport Police and 124 have been investigated by the Met.
At the scene - Greg McKenzie, BBC London
A forensic tent is outside the tower block marking the spot where the teenager died.
Residents have been telling me about rising tensions in the last few weeks. The block - just off a main road in Ilford - is known as a meeting point for drug dealers and people said the issue is "rampant".
They have also described a lot of "youth disturbance and violence" in the area and expressed their fear, anger and shock.
Officers have been coming in and out of the flats and they are trying to work out whether a burnt-out car is linked to the fatal stabbing.