Mayor of London Boris Johnson said:
"It is heart breaking to see the life of another young Londoner taken so tragically. My thoughts are with this young man's family at such a terrible moment."
"This horrific incident serves as an unwelcome reminder that although violent crime in the capital continues to fall, we must continue our fight to tackle youth violence and get knives off our streets."
More top news
Muhiddin Mire cut the throat of a stranger at an east London tube station "in revenge for the fight against IS", a court heard.
Rory Geoghegan claimed the lack of support he received from the Met shows how frontline officers are being taken for granted.
A registered sex offender who admitted grooming a 14-year-old girl and then sexually assaulting her has been jailed for over four years.