Police were called at 8.34am on Friday, 11 June to a report of a fight on Blyth Road in Hayes.
Officers attended the location and found a 15-year-old boy suffering from multiple stab wounds.
Colleagues from the London Ambulance Service and London’s Air Ambulance also attended and despite their efforts, the teenager sadly died at the scene.
A post-mortem examination will be held in due course. Formal identification has not taken place.
A crime scene has been established and cordons remain in place at this time.
Police have detained a suspect – no further details at this time.
Anyone who witnessed this incident or has information is asked to call police on 101 or Tweet @MetCC quoting reference Cad 1681/11Jun.
To remains 100% anonymous contact the independent charity Crimestoppers on 0800 555 111.