Five teenagers have been locked up for between 16 and 24 years for the "senseless" murder of a defenceless boy stabbed in the street outside his best friend's front door.
The gang of rival teenagers set upon Kyle Yule "like vultures" during a "revenge attack" on October 6 in Gillingham, Kent.
The 17-year-old was stabbed five times after he was chased from a parked car and died on the operating table in the early hours of the next morning.
The killing followed months of tit-for-tat attacks between teenagers in Medway towns.
Handing them all sentences of detention for life at Maidstone Crown Court on Thursday, Judge Adele Williams said: "This was a revenge attack. It was a senseless, ruthless and calculated killing, for which not one of you has at any stage shown any sign of remorse."
Victor Maibvisira, 19, Shezakia Daley, 18, both of Gillingham, Tyler Ralph, of Hertfordshire, and Ephrain Akinwunmi-Streets, of Sittingbourne, both 17, and 16-year-old Jordan Dania, of Croydon, were all convicted of his murder after an eight-week trial.
None of the defendants reacted to their sentences but some of their relatives, who were sat in the packed court room, fell to the floor in tears as they were led away.
The sentences will be served in youth detention centres until the defendants turn 21.
Ring-leader Maibvisira will serve a minimum term of 24 years, while the other defendants each have a minimum term of 16. Judge Williams warned they may never be released.
Kyle's mother Nikki, who burst into tears as she read a victim impact statement to the court, branded her son's killers "cowards" and said they had "ruined lives forever".
She said: "Kyle was loving, kind-hearted, warm, funny, handsome and full of life. He was my best friend.
"You were cowards running around with weapons.
"How dare you sit there and look forward to your birthdays.
"I had to arrange a funeral for my son when I should have been planning his 18th birthday."
During the trial, the court heard the five defendants, including Maibvisira who was known by his tag name V, were on East Street when they came across a Renault Clio with Kyle inside.
In a bid to get him out of the vehicle, an eyewitness told police the "group were smashing the car as if they were possessed".
Kyle escaped from the car and ran towards the home of his best friend where he was knocked to the ground and attacked in the front garden.
A witness told officers the group chasing him "were on him like vultures, kicking and punching him".
There had been a string of previous disputes between the two groups in the weeks and months before the attack, the trial heard, but Kent Police has insisted the killing was not gang related and there is not a problem with gangs in the area.
Akinwunmi-Streets, Daley, Ralph and Dania were granted anonymity during the trial due to their age but following the jury's verdict the judge allowed their names and the towns in which they lived to be reported.