"We have been informed of the passing of Damien Nash," team spokesman Jim Saccomano said Saturday night. "We are attempting to get more details. ... We do know it's true."
Officials at Christian Hospital in St. Louis said the 24-year-old Nash died early Saturday evening. The cause of death wasn't immediately determined.
Nash collapsed shortly after participating in the game benefiting a foundation named for older brother Darris Nash. The foundation raises money for heart transplant research. It was established last month, after Darris Nash received a heart transplant.
"The Denver Broncos organization is once again struck with profound sadness over the tragic loss of one of our players," team owner Pat Bowlen said in a statement. "This is a tremendous tragedy and our hearts go out to the entire Nash family."
The Broncos are still reeling from the slaying of Williams, who was shot once in the neck while leaving a New Year's Eve party in his rented stretch Hummer in downtown Denver hours after the season ended. His slaying remains unsolved.
"The Broncos family has suffered a great loss with the passing of Damien Nash," coach Mike Shanahan said from Indianapolis, where he was attending the NFL's scouting combine along with general manager Ted Sundquist. "I am stunned and deeply saddened by this tragedy, and send my deepest condolences to Damien's family."
Nash was from East St. Louis, Ill., and played two years at Missouri after playing at Coffeyville Community College in Kansas. A fifth-round draft choice by Tennessee in 2005, he played in three games for the Titans before his release.
The Broncos signed him as a free agent last season and he played in three games, rushing for 98 yards on 24 carries.