Superintendent Tim Alexander, from the borough of Brent, said: "Overnight we found ourselves in the unusual position of having to deal with three violent incidents in our borough of Brent.
"I understand the community’s concerns regarding last night’s events, but I would like to reassure the people who live and work in Brent that we remain a safe and vibrant borough that rarely sees incidents of such violence.
"One of the incidents was sadly the murder of a young woman in the prime of her life. However, I would like to confirm that we have a man in his 40s in custody and that we are not seeking anyone else in connection with this incident. I can also confirm that the victim and the suspect were known to each other and that the crime happened inside a private residential property.
"Earlier in the evening, the borough also had a shooting and a stabbing within two hours of each other. Whilst this is of concern, I’d like to reiterate that my officers are working around the clock to identify, locate and apprehend those responsible.
"The community can expect to see extra officers on the streets of Brent over the coming days and I would urge anyone who has any concerns to feel free to approach them. Anyone who would rather speak to an officer in private can do so by calling Brent police via 101 or contact your local neighbourhood policing team.
"I would encourage anyone with information about any of these incidents to call police on 101. You can also contact Crimestoppers anonymously by calling 0800 555 111 or online at crimestoppers-uk.org."