A 22-year-old man killed in a double stabbing outside a Tesco store in Kilburn, north-west London, has been named by police as Sven Badzak.
Detectives said Mr Badzak was chased by a group of males and was attacked after falling on Willesden Lane.
Mr Badzak's 16-year-old friend was also stabbed in the attack and remains critically ill in hospital, the Met Police said.
Ch Insp Guy Ellwood described the attack as "barbaric".
Officers were called to Willesden Lane at 17:40 GMT on Saturday where they found Mr Badzak injured.
Mr Badzak was taken to a hospital in central London where he later died, Det Ch Insp Darren Jones said.
He added that, at this early stage of the investigation, detectives believe Sven and his friend came into contact with a group of males who then chased them.
"As this group chased the pair, Sven and his friend became separated. Sven fell to the ground and was attacked by a number of the group.
"His friend was also attacked but managed to seek sanctuary in a shop. However, he remains critically ill in hospital."
Det Ch Insp Jones appealed for any witnesses who were in the Willesden Lane and Kilburn High Road areas at the time of the attack.
The murder investigation comes after another 13 people were injured in an "abhorrent" wave of knife crime across parts of the capital.
Throughout Friday night the Met was called to separate stabbings in other parts of Croydon, Chislehurst and Streatham.
One of the victims, a 22-year-old man, died after being attacked in the Wisbeach area of Croydon.
On Saturday afternoon another man, aged 24, was stabbed on Oakfield Road near West Croydon station.
Hours later, a 15-year-old boy was attacked on the Churchill Gardens Estate in Westminster, police said.
None of those victims suffered life-threatening injuries, the Met added.