A 13-year-old incoming freshman collapsed and died at a southwestern Illinois high school football practice.

The Madison County coroner identified the Granite City teen as Toney Graham. He died Wednesday afternoon at a preseason practice for Granite City High School.

Coroner Steve Nonn said that Graham collapsed suddenly in an air-conditioned school gym while stretching after players were fitted for uniforms.

Graham was reportedly joking with teammates before he fell, showed no outward signs of distress and reported no previous medical problems. He was taken by ambulance to a nearby hospital, where he was declared dead two hours later.

An autopsy on Thursday found evidence of heart disease. The official cause of death remains undetermined pending further investigation.