The teen was seriously injured when he was knifed in the torso, right hand and right cheek during the 2:40 p.m. clash at the fast-food joint on Eighth Avenue near West 51st Street in Manhattan, authorities said. 

A 19-year-old man was shot in the left arm and a 20-year-old man took a bullet to the back during a clash on 45th Street near 5th Avenue in Sunset Park, police said. 

NYPD Commissioner Jessica Tisch touted her officers' hard work to keep the peace Saturday night as the Knicks NBA championship sparked celebrations across the city -- with some fans marring the parties with violent incidents.