By Catherine Wylie, Press AssociationSyed Jamanoor Islam, 20, died in hospital after an "altercation" with a group while with friends in Wager Street, Mile End, east London, at around 4.45pm on Tuesday April 11.
Scotland Yard said three males, aged 18,15 and 17, were arrested in the early hours of Sunday morning in South Yorkshire on suspicion of murder.
An investigation was launched after police were called to reports of a stabbing, and officers found the 20-year-old suffering from stab wounds.
He was taken to an east London hospital where he was pronounced dead at just after 5.30pm.
Police said it is believed the victim was with friends in Wager Street and was approached by a group of males when an altercation began and he was stabbed.
A post-mortem examination gave the cause of death as a stab wound.
An 18-year-old man who was arrested on suspicion of murder on Wednesday and taken into custody at an east London police station has been bailed pending further inquiries to a date in April.
The Met's homicide and major crime command is investigating, and Detective Chief Inspector Tony Lynes said: "We are still keen to speak to anyone who was in the area at that time and might have seen what happened or who has any information about the circumstances."
Police said officers are keeping an open mind about a possible motive.
The three teenagers are in custody at a south London police station.
Anyone who can help is asked to contact the incident room on 020 8721 4868, via @MetCC, or Crimestoppers on 0800 555 111.