A BMW driver has been urged to come forward by police after a young man was stabbed to death in broad daylight in south-east London.
Emergency services rushed to Plumstead where a 24-year-old man was found with knife wounds around 4.30pm on Monday.
Detectives revealed on Tuesday that two men walked up to the victim in Grassdene Road before the attack.
He then staggered to nearby Bournewood Road where he was pronounced dead by medics who battled to save his life.
A 23-year-old man was arrested on suspicion of murder, in Bognor Regis, Sussex, on Tuesday afternoon.
He is being held a south London police station.
Scotland Yard have launched an appeal to trace a second man, described as black and wearing a white t-shirt, who is believed to have fled the scene of the attack in a BMW sports car.
Detective Inspector Will Reynolds, of the HMCC, said: "Whilst an arrest has been made I would urge anyone with information or witnesses to this incident to speak to us as soon as possible.
"I am particularly keen for the man seen leaving the scene in the BMW vehicle to come forward and make himself known to us.
“We believe he may hold vital information."
Resident Caroline Juby said: “There were police everywhere. There were some youths at the scene in distress and the family of the boy. They were screaming with grief, it was horrible to see and hear.”
Another neighbour said: “I spoke to the father of the stabbed boy at the police line. He was in shock. He just kept saying, ‘My boy has been stabbed’.”
He was rushed to hospital from the scene in Newnham Close where he was pronounced dead just after 5.35pm.
Four men, whose ages are currently unknown, have been arrested and are currently being held at police stations across London.