Detectives investigating the fatal stabbing of 16-year-old John Ogunjobi, 16 in Tulse Hill have today, Monday, 12 November, made four arrests.
Four men - aged [A] 22, [B] 20, [C] 21 and [D] 23 - have been arrested on suspicion of murder and taken to custody at south London police stations for questioning.
Officers are returning to the scene this evening, a week-on from John Ogunjobi's murder to appeal for witnesses.
Police were initially called to Greenleaf Close, Tulse Hill at 22.53hrs on Monday, 5 November.
Officers attended along with the London Ambulance Service (LAS) and found a John collapsed in the street with stab injuries.
Despite the efforts of paramedics, the male was pronounced dead at the scene at 23:41hrs. His next of kin are aware.
He had been formally identified as John Ogunjobi, 16, of Tulse Hill.
A post-mortem examination held on Thursday, 8 November, at Greenwich Mortuary gave cause of death as a stab wound.
An investigation is underway by detectives from the Homicide and Major Crime Command, led by Detective Chief Inspector Richard Vandenbergh.
DCI Vandenbergh said: "I am appealing to anyone who has information that could assist this investigation to come forward and speak to police.
"We believe the victim was attacked by a number of suspects and the altercation would have undoubtedly drawn the attention of those who were in the vicinity.
"Did you see or hear anything? If so, no matter how insignificant you think it may be, please call - your information could prove to be crucial."
Officers are also appealing to anyone who may have captured footage or images of the incident on their mobile phone to get in contact.
Anyone with information is asked to contact the incident room on 020 8721 4961 or call Crimestoppers anonymously on 0800 555 111.
You can also tweet information to @MetCC.