One man was stabbed to death on a day that saw seven knife attacks in the capital in just as many hours.
A gang used two cars to stop traffic before ambushing the victim, 21, in High Street, Harlesden at around 9pm on Tuesday.
One witness claimed it was a ‘revenge mission’ and told the Evening Standard: ‘I’ve seen the guy who died out there before. It looked like they knew who they were looking for.
‘The injuries were terrible, people were vomiting because of the extent of the wound.’
He ran into a bookmakers to get help and was rushed to hospital, where he was pronounced dead in just after 2.45am.
Seven men have been arrested in connection with the murder.
DCI Glen Loyd said: ‘We know 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?
‘I would like to ask anyone who filmed the assault on a mobile phone or who may have captured it on dash cam to call us.
‘It is important that we build up a picture of what happened on the High Street last night.’
It is the 39th violent death in the capital so far this year.
Another man, aged 28, is fighting for his life after he was stabbed outside a Tesco on Preston Road in Wembley, three hours earlier.
He remains in a critical condition in hospital.
The first stabbing happened at about 3pm in West Drayton, where a man was found with multiple stab wounds.
His condition has been deemed not life-threatening, Scotland Yard said.
Two men were taken to hospital around 8pm with knife injuries after a fight in another part of Harlesden.
At around 10pm, two 17-year-old boys were injured in separate stabbings in Mitcham.
Emergency services were called to Tamworth Lane and Morden Road.
Neither victim’s injures are believed to be life-threatening.