A large part of Ilford town centre was closed off on Saturday
A teenager stabbed to death in east London has been named by police as Nabeer Bakurally.
Mr Bakurally, from Forest Gate, east London, was stabbed through the heart during an attack on Ilford High Road in the early hours of Saturday.
Another youth, aged 17, is "serious but stable" in hospital with injuries which are not thought to be life-threatening.
Officers have been given more time to question two men, aged 23 and 24, who were arrested soon after the incident.
A 21-year-old man, who was arrested in Ilford on Sunday, also remains in custody.
Detectives said the incident happened after an altercation between two teenagers and a group of up to three other males. A weapon has been recovered.
A post-mortem examination showed Mr Bakurally had been stabbed through the heart.
Police are still seeking witnesses to the incident, which happened at about 0330 GMT.
Earlier Det Ch Insp John MacDonald said: "As the incident unfolded, we understand a group of people gathered in the Clements Road area, who I believe would have witnessed the incident.
"In particular, I am keen to speak to a young female in that group who may have had some interaction with the suspects prior to the attack."
A large section of Ilford town centre was cordoned off, including parts of Clements Lane, Clements Road and Ilford High Road, with several shops closed for the day.
A total of 28 teenagers have now died in violent incidents in London in 2008.