A murder investigation has been launched after a teenager was stabbed to death in broad daylight in Northolt.

Police were called by the London Ambulance Service at around 3.20pm on Tuesday to reports of a man knifed in Newnham Close, Northolt.

Officers attended and found a 19-year-old man with stab wounds.

He was taken to a north London hospital but was pronounced dead at 5.35pm.

Next-of-kin have been informed. Formal identification awaits and a post-mortem examination will be held in due course.

Three 19-year-old men and an 18-year-old man were initially arrested on suspicion of attempted murder. They have been further arrested on suspicion of murder.

All four currently remain in custody at separate London police stations.