Updated: Aug 21, 2008 10:41 AM EDT
KNOXVILLE, Tennessee (AP) -- A student fatally shot a 15-year-old classmate during a dispute Thursday at a Knoxville high school, and other teenagers watched in horror as the victim clutched his chest and fell to the floor.

Police block the entrance to Central High School in Knoxville, Tennessee, after reports of a shooting.
1 of 3 Police identified the victim as Ryan McDonald, a sophomore who lived with his grandmother and had alopecia, a condition that left him bald and the target of endless teasing as a child.
"He tried to have a tough exterior, like a shield, to fit in," his uncle Roger McDonald said. "He was a good kid ... who was dealt some bad cards in life."
The shooting happened shortly after 8 a.m. at the Central High School cafeteria, Chief Deputy Bill Roehl said, and the suspect was taken into custody minutes later on a nearby street.
The suspect and victim knew each other, Knox County School System Superintendent Bill McIntyre said.