A 19-year-old man has become the fourth teenager in as many months to lose his life to the surge in knife violence on London's streets.
The killing in Blackheath, south-east London, comes just a day after the new Metropolitan Police commissioner Cressida Dick vowed to tackle the growing problem of gun and knife crime in the capital.
The Met issued figures last week showing a 42% rise in gun crime in 2016-17, while knife crime was up 24% and knife violence resulting in injury was up by 20.5%.
There have now been seven teenage homicides in 2017, including four stabbings and three shootings, a Met spokesman said.
In the first four months of 2016, there had been two fatal stabbings of teenagers, while over the whole year a total of 12 teenagers died after being knifed.
A Press Association analysis of media releases by Scotland Yard suggests there have been 18 murder investigations launched into the stabbing deaths of victims of all ages since the start of the year.
The force always issues a press release in the event of a murder investigation, the spokesman added.
Earlier this month, three people were stabbed to death in little more than 24 hours in attacks in different parts of the capital.
The victims were Syed Jamanoor Islam, 20, Abdullahi Tarabi, 19, and Rene Richardson, 24.
In the latest killing, officers were called to Hervey Road with the junction of Begbie Road at around 8.10pm on Wednesday and found the 19-year-old with stab wounds.
He was taken to a south London hospital, where he later died.
The Met said his next of kin are aware and a post-mortem examination will be arranged in due course.
A Met spokesman said: "There have been no arrests and inquiries continue."
On the day before the latest killing, Ms Dick said knife and gun crime were a "huge concern".
She told the BBC Radio 4 Today programme: "The figures worry me. I want to bear down across the wide spectrum of violent crime.
"If it is the case that gun crime and knife crime are going up, that is of huge concern to me and it will mark out my commissionership, trying to bear down on violence in general and those two crimes in particular."