A man has been arrested on suspicion of murder after a 20-year-old was stabbed to death in north London. He was found fatally wounded on Roth Walk, near Finsbury Park, at about 3am on Saturday, Scotland Yard said. Medical staff tried to save his life but he died at the scene about 45 minutes later.

A second man, 21, found stabbed on Seven Sisters Road, was arrested on suspicion of murder, affray, and possessing an offensive weapon, the Metropolitan police said. He was taken into custody after being discharged from hospital.

Sadiq Khan tweeted:

The mayor of London said: “The Met police are using extra City Hall resources to fight this scourge and to remove violent criminals and weapons from the streets.

Police said inquiries were under way to trace the dead man’s family.

On Saturday night two men were stabbed after a fight outside a London tube station at rush hour. The pair were found with knife wounds on Upper Tooting Road, south London, near Tooting Bec Underground, at around 6pm, Scotland Yard said.

One man’s injuries were not life-threatening, while the condition of the other was not given. Images on social media showed several police vehicles at the scene and parts of the road cordoned off while officers made inquiries.

Less than half an hour later, paramedics were called to help a 14-year-old boy who had been stabbed in the leg in Lloyd Park, Walthamstow.

Another man died on Friday night after being seriously injured in an assault in Morden, south London, on Thursday. Police said they had established that the victim was involved in a fight in the street. A 31-year-old man was arrested on suspicion of murder on Friday and taken to a south London police station, where he remained in custody.