PITTSBURGH -- Burial services were held on Monday for a Duquesne student who died on Tuesday of natural causes.

The Allegheny County Medical Examiner's Office said a Duquesne University freshman died of a ruptured aorta on Tuesday night.

Authorities said Joe Irwin, 19, was found in his dorm room unresponsive at about 9 p.m. He was taken to UPMC Mercy Hospital, where he was pronounced dead.

Officials told Channel 11 that a ruptured aorta is a rare condition in someone so young, but it's often caused by a genetic defect victims never know they have.

"He never showed fatigue on the court, never mentioned anything to any of us that he had problems whatsoever. We're all devastated and shocked by this," teammate Devin Koehring said.

Irwin graduated in 2008 from Bethel Park High School where he was the co-captain of the school's volleyball team. Irwin played club volleyball at Duquesne.

"Always had a smile on his face. Always made us laugh at practice. He definitely will be missed on the team," said Koehring.

The volleyball team plans to sign a volleyball in Irwin's honor and give it to his family.