Garrett Reid was found unresponsive Sunday morning.  (AP)

Coach Andy Reid wasn't at the Eagles' Sunday morning walkthrough for what the team originally described as a "personal issue." In an official statement, Philadelphia general manager Howie Roseman said that Reid's oldest son, Garrett, was found dead in his room at Lehigh University, the site of Eagles' training camp, Sunday morning.

"I have some heartbreaking news to share," Roseman said. "It is with great sadness that I tell you that Garrett Reid, the oldest son of coach Reid, was found dead in his dorm room at training camp. This is a tough morning for all of us in the Eagles' family. Garrett grew up with this team and this makes this news even harder for us to process. Our hearts go out to [Reid's family]."

Garrett Reid, 29, was at Lehigh helping out with strength and conditioning during camp. 

"This news is heartbreaking for everyone in the Eagles family," team owner Jeffrey Lurie said. "Our hearts go out to Andy, his wife, Tammy, and their children."

Eagles players were informed of the news Sunday morning and were seen gathering in prayer on the field. Reid informed Roseman that he wants training camp to continue. 

The team has announced that offensive coordinator Marty Mornhinweg and defensive coordinator Juan Castillo will oversee the team in Reid's absence. Lurie said he expected Reid back this week.

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According to CBSSports.com's Jason La Canfora, Lehigh University police chief Edward Shupp said that a 911 call came in at 7:20 a.m. ET Sunday for a "nonresponsive male."  Attempts were made to revive Reid but those attempts were unsuccessful. There were no signs of suspicious activities, and the coroner's investigation is ongoing.

Authorities had few additional details about Garrett Reid's death, the Associated Press reported.

"What I can tell you is this morning we were contacted by the Lehigh campus police department and [were] requested to respond for the discovery of a deceased male," said Northampton County coroner Zachary Lysek told the AP. "We are conducting an investigation with the cooperation of the Lehigh campus police department and I personally pronounced Mr. Reid deceased at the scene."

Reid and his wife Tammy have five children, three of them boys. Garrett and his brother Britt had both struggled with drugs in the past, and Reid took a five month leave of absence from the team in 2007 to try to help his sons. Garrett Reid was sentenced from two-to-23 months in county prison and a year probation following a crash, after which he tested positive for heroin. However, Garrett Reid had appeared to have turned his life around in recent years.

In the midst of his legal troubles in his early 20s, Garrett Reid said he "got a thrill" out of being a drug dealer in a lower-income neighborhood just a few miles from his parents' suburban Villanova mansion, the AP reported.

"I liked being the rich kid in that area and having my own high-status life," Reid told a probation officer, according to court testimony in November 2007. "I could go anywhere in the 'hood. They all knew who I was. I enjoyed it. I liked being a drug dealer."

At his sentencing hearing, Reid told the judge: "I don't want to die doing drugs. I don't want to be that kid who was the son of the head coach of the Eagles, who was spoiled and on drugs and OD'd and just faded into oblivion."

Andy Reid is in his 14th year with the Eagles, the longest current tenure in the NFL. Owner Jeffrey Lurie was scheduled to meet the media at 1 p.m., for his annual state of the franchise press conference, but that has been cancelled, according to the team.

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