Police are appealing for anyone who witnessed the murder of a young man in Harlesden to send dash cam footage or to phone them.
Emergency services were called to Harlesden High Street just after 9pm last night following reports of a stabbing.
Detectives believe that the suspects arrived in two cars before blocking traffic in order to carry out the attack.
Anyone on the Number 18 bus may have filmed the assault on a mobile phone and motorists captured the crime on a dash cam.
The 21-year-old victim fled into a bookmakers to seek help before paramedics arrived.
He was found suffering from stab wounds and taken to hospital but was pronounced dead at 2.47am this morning.
Next of kin have been informed but formal identification is yet to take place.
A post-mortem examination will also be held soon.
Detectives have launched a murder enquiry.
Det Chf Insp Glen Lloyd, of the Met’s murder squad, said: “I am appealing for anyone who witnessed this violent attack to come forward and contact the incident room.
We know that the suspects blocked the road; this would have held up a number of vehicles including a Route 18 bus. Were you on this bus at 9pm?”
He added: “I would ask that anyone who filmed the assault on a mobile phone or who may have captured it on a dash cam to call us.
“It is important that we build up a picture of what happened on the High Street last night.”
Seven men were arrested at the scene on suspicion of offences including possession of an offensive weapon and attempted murder. They remain in custody.
A section 60 order has been put in place until 1.30am tomorrow covering Stonebridge, Harlesden, Welsh Harp, Tokyngton, Kensal Green, Dudden Hill and Preston Wards.
The order allows police to stop and search anyone whether or not they suspect the person of carrying a weapon.
Any witnesses to last night’s attack or those with information are asked to call the incident room on 020 8358 0100 or 101 quoting reference Cad 7897/23Apr,
Tweet @MetCC or call Crimestoppers anonymously on 0800 555 111.
Young people who either have information about violence or knife crime can visit fearless.org where they can pass on information anonymously.
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