Media reports say at least 13 British teenagers have been fatally stabbed this year.
In the latest stabbing incident, an 18-year-old man has died in a hospital after being attacked near a west London Underground station.

He is the thirteenth teenager to be fatally stabbed in the capital this year.
The man, who has not yet been formally identified was wounded near West Ruislip station during Monday's evening rush period.

Police have arrested a man in his 20s. He is now being questioned in a west London police station.