Alex Mulumbu died after he and two of his friends became involved in an argument with a larger group of teenagers near a bus stop in Lambeth.
During the dispute members of the gang disappeared into a nearby estate and returned armed with knives. In the fight that followed, Alex was stabbed in the heart and was left lying in a pool of blood on the pavement.
His distraught friends managed to flag down a passing car and get him to St Thomas' Hospital where he was pronounced dead shortly after midnight.
His father, Kamondo Mulumbu, from the Democratic Republic of Congo, visited the scene of his son's killing where he denounced Britain's knife culture. Speaking to reporters, Mr Mulumbu, who has six children, said: "Knives are out of control. Most young people are walking around [with them]. Alex was [a] good boy, he had nothing at all to do with knives."
Mr Mulumbu said his other son had called him on Thursday night to alert him that Alex had been stabbed. He said: "I went to the hospital - 10 minutes later the doctors asked me to come over and spoke to me. They said they tried to do the best they could but my son is no more in life." Police have yet to formally confirm the youngster's identity. Detectives are examining CCTV footage while carrying out an extensive search of the area.
The suspects are believed to be a group of 10 black men in their late teens who were wearing dark clothing. Detective Superintendent Richard Heselden, from the Specialist Crime Directorate Homicide Investigation, said that there must have been a considerable number of witnesses.
He said: "It was a warm summer evening and we are sure the streets would have been busy at the time of the murder."
Lucie Russell, the director of the campaign group SmartJustice, which promotes initiatives to tackle crime, condemned the stabbing. She said: "This is a terrible tragedy that a boy can lose his life in this way. Many young people are frightened and carry knives for their own protection, others see carrying a weapon as a badge of honour. "Communities would be safer if we focused on what's causing this fear, what's driving youth crime and investing in constructive work with young people at risk and more support for their parents." A post-mortem examination is due to take place at Greenwich, south London, this morning. The police spokesman said an inquest would be opened and adjourned at Southwark Coroner's Court "in due course".
Syed Kamall, a Conservative MEP for London, yesterday called for a European "knife summit" to pool ideas. Mr Kamall said it was not only London that faced the growing problem . He he has written to the European Commission president, Jose Manuel Barroso, urging talks on how to curb the growing menace on Europe's streets. He said: "Knife crime is a growing problem across European cities ... and we should be learning from the experiences of other countries to help reduce knife crime."