A man has died and another three have been injured after a stabbing in east London.
A man in his 20s died at the scene on Buckle Street, Whitechapel, the Metropolitan Police said.
Three other men with stab injuries were treated at the scene and taken to hospital.
Two people have been arrested on suspicion of GBH.
Officers were called to the scene just before 9am on Saturday and a large police presence remained in the area by the afternoon.
A man in handcuffs was seen being led out of Blakeney Tower on Buckle Street by several police officers, and an inside door was covered in brown paper.
A second handcuffed man was led out a few minutes later and taken away in a police van.
A forensics team could be seen inside the lobby near the lifts, while officers spoke to people as they entered and exited the building.
Police have asked anybody with any information, including pictures or video of the incident, to come forward.