A 17-year-old boy has been stabbed to death in Brixton, South London police have said.
The teenager was with his friend when they were chased and attacked at around 5.50pm last night.
A Metropolitan Police spokesman said the victim's next of kin have been informed but detectives are still awaiting formal identification.
His friend was not injured.
The attack took place in Adelaide Close on the Moorlands Estate.
Scotland Yard said the victim was with his friend on the way to the friend's relative's house in Brixton when the attack happened.
The suspects were described as two young black men.
Police were alerted to the incident at 5.52pm by London Ambulance Service. The victim died in an ambulance en route to hospital at 6.42pm.
Officers are investigating if the killing is linked to another stabbing incident yesterday when a 17-year-old boy was attacked outside Norwood Bus Garage, Ernest Avenue, West Norwood at around 1.15pm.
He was taken to a south London hospital where he is in a stable condition with serious injuries.
A male, in his late teens, was arrested in connection with the incident and is being questioned by detectives.
Commander David Zinzan, in overall charge of policing in south-east London, said: "Following the fatal stabbing of a 17-year-old boy in Brixton and the wounding of another 17-year-old boy in West Norwood on Friday, and other serious stabbings in Lambeth borough in the last few days, police have increased patrols in and around the borough.
"Extra officers have been drafted in to reassure and protect the public, and to act as a strong deterrent to anyone thinking of committing further violence in the aftermath of these incidents."
He added: "Witnesses have come forward and detectives from the Specialist Crime Directorate and Lambeth borough have been working around the clock to gather evidence and identify those responsible.
"Officers are investigating these two cases and are keeping an open mind over whether they are linked at this stage."