Three teenagers were given life sentences Thursday for leading a gang attack on a schoolboy who was stabbed and killed in South London. A judge at the Old Bailey said Dale Green must serve at least 15 years for killing Nicholas Pearton, while Lamarr Gordon was ordered to serve 14 years and Joseph Appiah, 16, was given a 12-year minimum sentence, The Independent reported. Four other teens were given sentences of up to 10 years for manslaughter. Nicholas, 16, was attacked as he walked home from school in May 2010. He bled to death on the floor of a takeout restaurant. The attack allegedly stemmed from a feud between rival gangs that led to a fight in school. Prosecutors said the teens were in the Shanks and Guns Gang, The Sun reported. The attackers chanted "SG boys" and a security camera captured Gordon and Green shaking hands on a bus after the stabbing. The group behaved "like a pack of wild animals," a prosecutor said. Gordon got into a fight with prison officers escorting him from the courtroom and ended up being carried out.