A 21-year-old man was fatally stabbed on a London high street after a gang used two cars to block traffic.
Drivers were disrupted on Harlesden High Street at about 21:00 BST on Tuesday, when murder detectives believe the victim was wounded.
He staggered into a betting shop to appeal for help, but died in hospital at about 02:50 BST.
Seven men were arrested nearby and are being questioned by police, who are treating the man's death as murder.
The Metropolitan Police said they were being held on suspicion of offences including possession of an offensive weapon and attempted murder.
The victim's next-of-kin have been informed. A post-mortem examination is due to be held later.
Some 25 people have been stabbed to death in London so far this year.
There have been four other stab attacks in London since Tuesday afternoon.
The first happened at about 15:00 in Camomile Way, West Drayton. A man was found with multiple stab wounds but his condition is not life-threatening, police said.
Seven people have been arrested for offences including GBH, assisting an offender and possession of firearms.
At about 18:30, officers were called to reports of two men fighting in Preston Road, Wembley.
They found a 28-year-old man with stab wounds. He has been taken to hospital and is in a life-threatening condition.
There have been no arrests, police said.
At about 22:00, two 17-year-old boys were hurt in separate stabbings in Mitcham.
Police and paramedics found the boys in Tamworth Lane and Morden Road.
Neither victim's injuries are thought to be life-threatening and no-one has been arrested.