Chicago Bears defensive end Gaines Adams died Sunday morning of cardiac arrest, the Greenwood, S.C., county coroner said. He was 26.

Greenwood County coroner James T. Coursey told ESPN that Adams, a Greenwood native, was taken to the emergency room at Self Regional Hospital, where he was pronounced dead at 9 a.m.

Adams, who had just completed his third season in the NFL, went into cardiac arrest at his family's home early Sunday morning, said Marcia Kelley-Clark, chief deputy coroner for Greenwood County.

The autopsy showed Adams had an enlarged heart, a condition Kelley-Clark said can often lead to a heart attack. But Adams' relatives didn't know about it.

"Nobody was aware of any kind of medical condition," Kelley-Clark said.

Toxicology tests are being run by the State Law Enforcement Division, though drug use was not suspected as a factor in Adams' death. However, those results probably will not be available for at least two months, Kelley-Clark said.

"I remember him at the 2007 draft as a fine young man," NFL commissioner Roger Goodell said of Adams on Sunday. "Our condolences to Gaines' family, his teammates on the Bears and Buccaneers, and their organizations on their loss."

In 47 games over three seasons with the Bears and the Tampa Bay Buccaneers, Adams had 67 tackles, including 13.5 sacks.

"We are stunned and saddened by the news of Gaines' passing," the Bears said in a statement. "Our prayers are with his family during this difficult time."