22 (11 from both teams).
One player, Chris Henry, died off the field after falling out of the back of a truck. No player died on the field in 2009.
In terms of field speed, Devin Hester.
any player on the field or the head coach
Ironically, the only NFL player to have ever died on the field did so with no one touching him. Chuck Hughes was only 28 years old when he died of a heart attack on the field in 1971.
Until it is considered safe to move the player.
there are six refs in a NFL football game
Chuck Hughes. He is, to date, the only NFL player to die on the field during a game. Thomas Herrion died shortly after a game in 2009, in the lockers, but not actually on the field.