London's murder rate is soaring because "feral" youths are stabbing people multiple times with zombie knives, making it virtually impossible for paramedics to save them, one of Scotland Yard's most senior officers has suggested.

Metropolitan Police Assistant Commissioner, Martin Hewitt, said the level of violence had got significantly worse over the past five years with his officers now routinely administering "trauma medicine" on the streets of the capital.

His comments came as a 20-year-old man was found fatally stabbed in north London after reports of a fight on Wednesday evening.

The Metropolitan Police said officers were called shortly after 6.30pm to reports of a brawl between men armed with baseball bats in Cavendish Road, Edmonton. The victim had stab wounds and was pronounced dead at the scene.

A 16-year-old boy was later arrested on suspicion of murder and was in hospital for treatment before being taken to a north London police station for questioning, officers said.

Speaking at a knife crime summit, organised by the Mayor of London, Mr Hewitt said the trend towards using so-called zombie knives was making medics' jobs even more difficult because of the seriousness of the wounds being inflicted.