The teenager was found with stab wounds after police were called to reports of a fight in Burket Close, Hounslow, at 12.15am.

He was treated by ambulance workers but died at the scene, the Metropolitan Police said.

Four men - aged 21, 27, 31 and 71 - have been arrested on suspicion of murder.

The teenager's next of kin has been informed and are being supported by specialist officers.

Detective Superintendent Figo Forouzan said: "This is an extremely sad incident that will understandably cause concern in the community.

"I would like to reassure the community that we will carry out a thorough investigation to ensure those responsible are brought to justice.

"Whilst we have made arrests in this investigation, I would like to seek assistance from the public.

"I continue to appeal to anyone who has any information about how the events unfolded or anyone who may have captured the incident on their phone, dash cameras or doorbell footage to make contact with the police immediately."