Two teenagers are being held in custody on suspicion of murder after a 19-year-old boy was stabbed to death in Frampton Park Road, Hackney.
The victim, who has not been named by police, was found at around 4pm on Monday with multiple stab wounds.
Paramedics battled to save him at the scene but he died in hospital.
A 19-year-old was arrested within hours of the incident and police have now also arrested a 16-year-old.
A police spokesman said detectives are keeping an open mind about the motive behind the stabbing and have appealed for information.
Residents said the victim was chased before he was stabbed and police have been examining a blue Vauxhall Astra believed to have been used by the suspects.
Anyone who was in the area around the time of the attack, witnessed what happened or has any information that could assist the investigation, should call 020 8345 3775. To remain anonymous call Crimestoppers on 0800 555 111.