Officers in Hillingdon are investigating a fatal stabbing.
Police were called at 4.38pm on Thursday, 7 November to reports of a stabbing at High Street, Uxbridge.
Officers and London Ambulance Service [LAS] attended. A teenage boy at the scene had suffered a stab wound to the chest.
The injured male was taken by London Ambulance Service to a west London hospital where he was pronounced dead at 5.25pm.
A post mortem examination will be scheduled in due course.
Enquiries are underway to notify next of kin.
A second male, also aged teens, had suffered a knife injury to the ear. His injuries are not life threatening.
A 17-year-old male has been arrested on suspicion of murder and taken to north-west London police station for questioning.
The Specialist Crime Command have been informed and DCI Noel McHugh will be leading the investigation. He said: “This is a tragic loss of life. A young man with his whole life ahead of him has been fatally attacked. We are doing everything we can to find those involved. One male in currently in custody after being arrested on suspicion of murder.
“We need to hear from those in and around the area. Do the right thing and call police with what you heard and saw. Equally if you captured footage of the incident on your mobile phone before at any point of the incident, please contact my team who are ready to take your call.”
Anyone who witnessed this incident or has information is asked to call police on 101 quoting 5537/7NOV, Tweet @MetCC or call Crimestoppers anonymously on 0800 555 111.