A man was stabbed to death in Brent on Sunday night (April 15) during another evening of shocking violence in the capital.
The 26-year-old victim died in hospital following the fatal attack in Zenith Close, Colindale.
Metropolitan Police and emergency services were called just before 6pm.
A man was found with stab injuries at the scene and rushed to a central London hospital by London Ambulance Service, but he died later that evening.
Police are trying to trace the victim's next of kin and formal identification awaits.
Officers arrested a 34-year-old woman at the scene of the incident on suspicion of murder.
She was taken to a north London police station where she remained in custody on Monday morning (April 16).
According to police, the woman and the victim were known to each other.
A crime scene remains in place at the scene and enquiries into what happened are continuing.
A Met Police spokesman said: "A murder investigation has been launched following the death of a man in Colindale. Police were called at 5.58pm on Sunday April 15 to Zenith Close, Colindale, to reports of a stabbing.
"Officers attended along with London Ambulance Service and London's air ambulance."
"A 26-year-old male was found at the scene suffering stab injuries," the spokesman added.
"He was taken to a central London hospital by London Ambulance Service, where he was pronounced dead later that evening."
A post-mortem examination will be scheduled in due course.
Another night of violent knife crime in London
There were three further stabbings reported in London on Sunday night.
A woman in her 30s was stabbed to death in Brixton. Officers were called to a residential address in Sudbourne Road, at around 6.36pm, where the victim was pronounced dead at the scene.
A man in his 20s has been arrested on suspicion of murder and is in custody at a south London police station.
Detectives are investigating two further stabbings in north London, one of which left a teenager fighting for his life.
Officers were called to Alexandra Palace on Sunday at around 9.30pm where an 18-year-old man was found suffering stab injuries. He was taken to a north London hospital where his condition was described as critical.
A 19-year-old man was arrested near the scene and taken into custody. Following further inquiries, a second male suffering stab injuries was found at an address in Southgate. He is being treated at a north London hospital and his injuries are not believed to be life-threatening.
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