“My team has established that the attackers were armed with at least one firearm, knives and a samurai sword. Some, or possibly all, were riding bikes.
“I know that people may be reluctant or afraid to speak with police, but making a single call could help to remove dangerous, violent individuals from your area and all information provided will be treated in the strictest confidence."
There have been no arrests and enquiries continue. A damaged car was also found at the scene, which remains cordoned off by police.
The killing came a day after a man was stabbed to death at a youth club in Brixton, south London.
The 23-year-old victim was murdered on Thursday in what police described as a “premeditated and targeted” attack.
Detective Chief Inspector Richard Vandenberg said the “incident started outside the club before the victim was chased inside and attacked”.
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East Dulwich stabbing: Police on scene after man knifed to death in London
“The youth club was open at the time and sadly many young people present would have witnessed what unfolded,” he added.
"Many of them will be shocked and traumatised by what they saw and perhaps fearful of potential reprisals if they speak to police. I would urge them to get in touch.”
It came after the Metropolitan Police commissioner Cressida Dick said fatal stabbings involving victims under 25 in London were starting to fall.
Police have called for increased funding to tackle rising violent crime, while critics have blamed government budget cuts to youth services and preventative work.
Anyone with information on either incident is asked to call police on 101 or Crimestoppers, anonymously, on 0800 555 111.
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