INDIANAPOLIS, Feb. 25 -- David Canter spent part of Friday afternoon apologizing to his client, Denver Broncos running back Damien Nash, for not being able to attend Nash's charity basketball event in St. Louis because he would be in Indianapolis at the NFL scouting combine.

Nash told him not to worry, that the two would see each other at a wedding in a few weeks.

The next day, Canter received phone calls, first from a reporter saying that Nash had collapsed and died shortly following the game, and then moments later from Broncos officials, who confirmed it.

Nash, 24, was pronounced dead at Christian Hospital in St. Louis, though a cause of death has not been determined. Nash collapsed shortly after participating in the game benefiting a foundation named for his older brother, Darris Nash. The foundation raises money for heart transplant research and was established last month after the elder Nash, 25, received a heart transplant. Canter said that Darris Nash realized he had a heart ailment after being successfully revived after collapsing while playing basketball.

"When things like this happen, it doesn't seem real. It was probably the best week I've ever had with Damien as a client," Canter said. "I literally talked to him 15 or 20 times before the event. His brother meant so much to him."

Nash is the second Broncos player to die in just less than two months. After a New Year's Eve party in downtown Denver, defensive back Darrent Williams, 24, died after being shot in the neck during a drive-by shooting. His slaying remains unsolved.

"The Broncos family has suffered a great loss with the passing of Damien Nash," Broncos Coach Mike Shanahan said from Indianapolis, where he was also attending the scouting combine along with Denver General Manager Ted Sundquist. "I am stunned and deeply saddened by this tragedy, and send my deepest condolences to Damien's family."

Some of Nash's Broncos teammates, including running back Tatum Bell, attended the game, which was held in suburban St. Louis, Canter said.

According to Canter, the basketball game ended Saturday between 5 p.m. and 5:30 p.m. Central time. Nash went home and collapsed. He was pronounced dead at 6:41 p.m.

"When someone 24 years old in perfect health collapses, something isn't right," Canter said. "This was supposed to be a celebration that his brother had gotten a new heart, that he was a new father and that he was starting to have some success in the league. This was supposed to be a family event."

Nash was from East St. Louis, Ill., and played two years at Missouri after playing at Coffeyville Community College in Kansas. He was drafted by Tennessee in the fifth round of the 2005 draft and played three games for the Titans before signing as a free agent with Denver.

"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 Associated Press contributed to this report.