Cribbs' helmet flew off from the force of the contact and his head slammed onto the ground.
He remained motionless on the turf, his arms sprawled and his eyes closed for a few tense moments.
Players from both teams got down on their knees and began praying, including Ellerbe.
"You ain't really trying to go out there and try to hurt somebody," he said. "It's a part of the game, but you never do it intentionally. I thought he had just fumbled the ball; I didn't know he went to sleep."
After several minutes, Cribbs regained consciousness and was helped to the sidelines.
It was a scary moment for a player who suffered at least one other concussion two years ago against the Pittsburgh Steelers.
"He is the soul of our special teams," kicker Phil Dawson said. 'When he went down that was a big hole to fill. You can't replace Josh. He's so valuable to what we do."