Last year, a total of 28 teenagers died in violent attacks in the city
A teenage girl and a man have been arrested in connection with the murder of a 19-year-old in north-west London.
Kul Hawadleh, of Kingsbury, north-west London, died after being stabbed at a petrol station in Wealdstone, last Thursday evening.
In the incident, another 19-year-old suffered stab wounds to his chest.
A man in his early 20s was held on suspicion of murder and a girl, believed to be 17, on suspicion of assisting an offender.
Police said Mr Hawadleh and his friend had been with two others as they put petrol in a car at the High Weald Service Station, when they were approached by four to five youths, aged in their teens or early 20s.
There was an argument between the two groups before the stabbings and the suspects ran off.
On Thursday, a week after Mr Hawadleh's death, police will distribute posters and leaflets near the murder scene appealing for information and witnesses.
Acting Det Ch Insp John Oldham said: "Kul's friends and family are distraught. They cannot comprehend why Kul is no longer with them and they want to know who took his life.
"With the help of the community we need to identify those people responsible."
Mr Hawadleh's friend who was also stabbed is recovering in hospital and is in a stable condition.
Two men, aged 20 and 22, also arrested in connection with the stabbing, have been released on police bail.