Report by Gregg Easteal
Jack Woodley was fatally stabbed in the back during an assault by a gang of teenage boys who had gone out "looking for any excuse to attack someone", a court has heard.
Newcastle Crown Court heard he was punched and kicked, stamped on, and stabbed with a 25cm long "Rambo style" knife.
Prosecutor Mark McKone QC said Jack and the 10 defendants had been to the Houghton Feast festival before the attack on 16 October last year.
The 10 defendants, who cannot be named for legal reasons, are all charged with murder, with an alternative count of manslaughter.
Mr McKone said one of the teenagers had already pleaded guilty to manslaughter, admitting that he stabbed Mr Woodley but denying that he intended to kill him.
The other nine defendants, who were all aged between 14 and 17 at the time of the attack, deny both charges.
Mr McKone told the court one of the defendants first attacked Mr Woodley, and the others "joined in". He said one of them was heard shouting "get the chopper" - referring to the knife - in mobile phone footage of the incident.
The court heard one of the defendants was "armed with a very dangerous knife", while another admitted taking a knuckle duster out that night, but denied hitting Mr Woodley with it.
Mr McKone said: "The prosecution say, based on the available evidence, that the defendants went out looking for serious trouble that day."
He said the defendants "surrounded and isolated Jack", covering their heads as they prepared to attack him.
He told jurors Mr Woodley was outnumbered as the group "not only attacked him but prevented him from escaping and other people from helping him".
The court heard Mr Woodley died the next day, after "valiant attempts at the scene and in hospital" to save his life.