Two 15-year-old gang members who murdered an innocent teenager with a "Rambo-style knife" in a revenge attack have been handed life sentences.

The boys were both aged just 14 when they took a minicab to look for youths in the Harrow area of west London to seek retribution against rival gang members for an attack on one of their own.

Hussein Ahmed, 19, described as a "peaceful" university student, suffered massive blood loss and died in hospital three days after he was stabbed once in the back outside South Harrow Tube station on November 18 last year.

A 17-year-old was stabbed in the arm and stomach while another boy, also aged 17, narrowly avoided injury as a knifeman slashed the sleeve of his jacket.

After the eight-minute rampage, which took place during rush hour, the attackers returned to the waiting minicab, telling the unwitting driver: "Drive boss."

The driver described the teenagers as "happy" as they left the scene, "shouting and gesturing" at their dying victim.

Both 15-year-olds cried and wailed in the dock at the Old Bailey last month as they were convicted of murder as well as the wounding and attempted wounding of the two 17-year-olds.

"The way you behaved that night showed a total disregard for human life," Judge Anthony Leonard QC told them as he sentenced them to detention for life.

The boy found to be the stabber was told he must serve 16 years, while the other must serve at least 14 years before he is considered for parole.

The judge said the use of disposable surgical gloves by those carrying the knives was "chilling evidence" of the planning involved in the attack.

"You have been convicted of murder, arising from a revenge attack on what you believed to be members of a rival gang," the judge told them.

"The use of knives in the hands of young people who injure and kill without regard for the sanctity of human life is all too prevalent in London."

A 16-year-old youth was cleared of involvement, while a fourth suspect was said to have fled abroad.