(Minneapolis, MN) -- A 15-year-old stabbed in the back at Washburn High School last night is in stable condition. Minneapolis Police say the teen was stabbed during a brawl inside the school's auditorium just before 8 p.m. Shots were fired during the fight. Three shell casings were found and two teens were taken into custody. A Glock handgun with a 50-round magazine was recovered at the scene. Police are looking for a third teen suspect in connection to the stabbing. They don't know what led to the fight. It's not yet known if the teenagers were Washburn High students.