A teenager has been stabbed to death in east London. The 17-year-old victim was chased through an estate in the east London borough of Hackney by up to 15 people before being killed.

Police responded to reports of an assault at about 23:15 BST on Friday (4 September). The teenager, who has not been formally identified, was found with multiple stab wounds on the St John's Estate in Hoxton. He was pronounced dead at the scene by paramedics at 11.47pm.

A witness, who did not want to be named, said she watched the horrifying scene unfold through the window of her flat, as the teenager was chased through the estate and killed "in a brutal manner".

"There was a big chase," she explained. "They ran through the estate, some on bikes, some on foot. By the end of it when he died there were about 15 people around him. I just heard the screams, the cries - a primal scream of death. I could really hear it. I don't know if it was one of his friends who realised that he was dead but it was the most echoing, crying noise."

The witness said police arrived at the scene quickly and tried in vain to save the boy. "One of the policemen actually worked on him, CPR, for about 15 minutes. He really fought for him. The copper was just unbelievable," she said.

Confirming the reports Det Ch Insp Andy Partridge said: "A young man has lost his life in a brutal manner and I am appealing to anyone who was in the area last night and witnessed this attack to come forward and speak to police."

Officers believe they know the identity of the victim and are in the process of informing his next of kin. A post-mortem examination will be held in due course, the Met said. Large sections of the estate remained cordoned off today, as police trawled the site for evidence. No arrests have been made.

Candles have been lit in tribute to the victim, who is the ninth teenager to lose his life following a knife attack so far this year in London. The boy is the second teenager to be stabbed to death in London in two days. On Thursday Shaquan Mario Fearon died from a stab wound to his leg after a fight at a block of flats in Brockley, south-east London.

Anyone with information is asked to call police on 020 8358 0300, or contact Crimestoppers anonymously on 0800 555 111.