Four gang members have been convicted of murdering a 15-year-old boy who was chased by a group of boys on bicycles.
Negus McClean, of Edmonton, suffered multiple stab wounds after being chased by a group - described in court as a "hunting posse" - in April 2011.
Eighteen-year-olds Billal Lariba and Brandon Hamilton, Tershan Edwards, 19, and 16-year-old Travis Bowman were given life sentences at the Old Bailey.
Judge John Bevan said the "ghastly" killing was "cowardly beyond belief".
Hamilton, of Broad Oak Avenue, Enfield, was told he would serve at least 19 years; Lariba, of Mayall Close, Enfield, was ordered to serve a minimum of 16-and-a-half years, Edwards, of St Albans, Hertfordshire, must serve 17 years and Bowman, from Enfield, will be in prison for at least 12-and-a-half years.
The prosecution said all were members of the Enfield EN3 Get Money Gang (GMG).
The gangs operated "on a parallel universe" intent on meting out reprisals and refusing to co-operate with police, the court was told.
Judge Bevan added: "Lack of self-control and moral values is at the heart of it."
Yasmin Latif, 17, of Enfield, was found guilty of perverting the course of justice and given a 12-month detention and training order.
The stabbing happened in Westminster Road on 10 April 2011.
The court heard that Negus, a member of Edmonton's N9's Dem Africans group, was the third person in a week to be stabbed as part of a postcode rivalry between the gangs.
The first two victims survived.
'No respect for life'
Simon Denison QC, prosecuting, said: "A group of seven boys from the GMG gang rode out of EN3 on bicycles, like a hunting posse, south into N9, in order to carry out that attack.
"Negus came off his bike and he was attacked. He was knocked to the ground and repeatedly stabbed in the chest and in his legs.
"A metal knife that was used to stab him was driven down into him with such force that the blade snapped off the handle.
"Negus was left lying on the pavement, blood pouring from his wounds.
"He lost a lot of blood very quickly and died that evening in hospital."
Negus's mother Ingrid said in a statement to the court: "My heart is broken.
"Negus died just before his 16th birthday. He did not get to finish school. There was no prom for him.
"I was picking out his coffin on his birthday."
Of her son's killers, she said: "I am angry and hate what they have done.
"It seems these young boys have no respect for life, even their own.
"One day, if they become parents, they will think about Negus and the pain they have caused."