The 17-year-old was fatally stabbed in the street during a fight in front of party-goers in Granville Road, Brent, northwest London.

The teenager died at the scene of the incident, which took place around 11.30pm on Friday. His family have been informed.

Another male, also believed to be 17, was taken to hospital, as was a woman in her early 20s, who suffered a hand injury.

On Saturday, an 18-year-old man was arrested on suspicion of murder and taken into custody, as the Metropolitan Police called for party-goers who may have witnessed the incident to come forward.

A large area, including at least three roads, was cordoned off on Saturday afternoon, with forensic officers seen working outside an apartment block and a community centre, around a five-minute walk from each other.

Dozens of police officers were in the area, telling residents that cordons would be in place for the remainder of the weekend.

Rayan Assoui, 43, who lives nearby, said there have been many similar incidents in the area over the past few months.

He went on: "This area is getting worse, it's not good, for this to happen to a young person is very sad."

Detective Chief Inspector Mark Rogers of the Metropolitan Police said: "We believe that there was a fight following a birthday party, which would have been attended by a number of people.

"I would urge anyone who was there, and who has not yet spoken with officers, to please come forward. It is vital that we establish what happened."

Chief Superintendent Dan Knowles, in charge of the North West Command Unit, said: "I know that the community will be shocked by this incident in which a young man has lost his life.

"We shall be working with our colleagues from Specialist Crime to ensure that this investigation proceeds as quickly and thoroughly as possible."