According to ESPN he was shot in the head in Nashville - very sad news, he was one of the toughest quarterbacks of recent years but definitely not a player I would associate with any sort of trouble (although at this stage very little is known as to what happened).
http://sports.espn.go.com/nfl/news/story?id=4306275
http://sports.espn.go.com/nfl/news/story?id=4306275