Detectives investigating the murder of teenager Hani Abou El Kheir are to urge people to come forward with information, less than 24 hours after arresting a further eight people in connection with his death.
On Saturday night four males were arrested on suspicion of murder and one male and three females on suspicion of assisting an offender. They were being held in custody at various police stations, Scotland Yard said.
Hani, 16, was stabbed to death on Sunday in Pimlico, central London, last Sunday in an attack by a group of people believed to have been wielding knives and swords. Police were called to Lupus Street at 6.50pm, and Hani was rushed to Kings College Hospital, where he later died.
A week after the attack detectives will return to Lupus Street on the edge of Pimlico, one of London's most affluent suburbs, to redouble their efforts in the hunt for his killers.
From 6pm officers will appeal directly to the community of Churchill Gardens Estate, where Hani lived, to come forward and help with their investigation. Leaflets will be handed out to residents over the next few days, including an appeal from Hani's mother, Pauline Hickey, with whom he had an "unconditional and unbreakable bond", and ones from other members of his family and his girlfriend.
Det Chief Insp Neil Attewell of the Met's Homicide and Serious Crime Command said: "The tragic events of last Sunday have left Hani's mother and wider family completely devastated. I am directly appealing to the parents and carers of those believed to be involved - if you have the slightest indication that your child may have been involved in this incident I encourage you to get them to hand themselves into the police."
Police believe at least 10 people were involved in the incident and are keeping an open mind regarding a motive.
A post-mortem examination on Tuesday found Hani died from multiple stab wounds.
The arrests last night bring the total number arrested to nine. On Thursday a 20-year-old man was arrested in north London on suspicion of murder and bailed until late March.
Witnesses or anyone with information is asked to contact the incident room on 020 8345 3715 or Crimestoppers on 0800 555 111.