KANSAS CITY, Mo. - Aaron O'Neal, a 19-year-old Missouri redshirt freshman linebacker from suburban St. Louis, died Tuesday, hours after he collapsed during a voluntary conditioning workout in Columbia.

A cause of death has not been determined; an autopsy will be performed.

The hour-long workout, run by Missouri director of strength and conditioning Pat Ivey, was strictly for conditioning. The 12 players in attendance were in shorts and shirts and not in pads. No football plays were run.

Workouts such as this are common at major college programs. And in accordance with NCAA regulations regarding off season conditioning programs, no football coaches-including Missouri head coach Gary Pinkel - were present.

Pinkel, who was out of town at the time of the workout, expressed sadness in a statement released by the university late Tuesday night.

"I can't begin to express how deeply saddened we are by the loss," Pinkel said. "Aaron was a quality young man who was well-liked and respected by his teammates and coaches. We are all very shocked and hurt right now, but the most important thing we can do is to focus on Aaron's family and to assist them in any way we can."

By The Kansas City Star