A reserve cornerback on Long Beach (Calif.) Poly’s football team has died, the school confirmed to the Long Beach Press Telegram.

Frank Murphy, a senior at Poly who was part of the school’s academic magnet program, died Thursday night.

When reached by USA TODAY High School Sports’ Cam Smith, Long Beach Schools Spokesman Chris Eftychiou offered the following statement, giving additional insight into Murphy’s final hours.

We received word that Frank died apparently of natural causes while engaging in some sort of sports activity off campus after school. Early information was that he began having trouble breathing and that this happened somewhere in Fullerton. The school has lost a well-liked student athlete. He was known for his radiant smile. The counselor and coaches are working with students at the school and we send our sincere condolences to all of Frank’s family and friends.

Tributes began popping up on Twitter as news of Murphy’s passing spread.