A woman was knifed to death and another injured during a double stabbing in Wembley.
The 27-year-old victim died at the scene in Neeld Crescent while a second woman, 28, was rushed to hospital. Her injuries have been assessed as non-life threatening.
Two women were found by officers suffering multiple knife injuries after being called to the street in north west London at 10am on Tuesday.
A man, 24, and a woman, 23, were arrested on suspicion of murder at the scene.
Another man, 23, has been arrested on suspicion of murder in Harrow at 6pm after a police appeal to locate him.
He was taken into custody at a north London police station.
Both men remain in custody and the woman has been released without further action.
An investigation was launched after police were called to reports of a stabbing at a residential property.
Officers attended along with the London Ambulance Service and two women were treated for stab injuries.
Detective Chief Inspector Linda Bradley, from the Met’s Specialist Crime Command, said: “This has been a fast-moving investigation and I would like to thank the public for sharing our appeal for information about this man. He is now in custody.
“I recognise the significant concern this incident has caused in the community and I would like to reassure the public that a dedicated team of detectives are working to establish what happened.
“Local officers will remain in the area over the coming days to respond to any concerns.”