A 14-year-old boy was riding a moped moments before he was fatally stabbed, according to police.
Detectives say he was involved in a collision with a car in Leyton, east London, just before 6.30pm, yesterday
Three men then got out the vehicle and stabbed the victim, leaving him to die in a pool of his own blood, before speeding off.
Police and paramedics tried to save the lad, who has not been named, but he was pronounced dead at the scene just before 7.10pm.
He is the youngest murder victim in the capital since 14-year-old Corey Junior Davis, was fatally shot in Forest Gate, east London, in September 2017.
Last year 24 teenagers were among more than 130 people murdered in the capital.
The latest victim is the first teenager to be killed in London this year, but the fourth person to be murdered in just eight days.
A Met Police spokesman said: “Police were called to Bickley Road shortly before 6.30pm on Tuesday to reports of a road traffic collision.
“Officers and paramedics from the London Ambulance Service attended.
“A 14-year-old boy was found with stab injuries.
“It has now been established by detectives the boy was riding a moped that had been involved in a collision with a car.
“It is believed that three males got out of the car and then stabbed the victim before returning to the vehicle and driving off.
“Despite efforts of paramedics, he was declared dead at 7.09pm. Next of kin have been informed.”
He added: “A crime scene is in place.
“The Homicide and Major Crime team has been informed.
“There have been no arrests. Enquiries continue.”