ARTICLE 3. A live ball becomes dead and an official shall sound their whistle or declare it dead:
b. When any part of the ball carrier’s body, except the hand or foot, touches the ground or when the ball carrier is tackled or otherwise falls and loses possession of the ball as they contact the ground with any part of their body, except the hand or foot [Exception: The ball remains alive when an offensive player has simulated a kick or at the snap is in position to kick the ball held for a place kick by a teammate. The ball may be kicked, passed or advanced by rule].
Approved Ruling 4-1-3 I. While A1 is holding the ball for a place kick, Team B plays the ball by (a) recovering a loose ball, (b) snatching it from A1 or (c) batting it from his hands. RULING: (a), (b) and (c) The ball remains alive. In (c) the batting by Team B is legal and results in a fumble.