When a runner has come into contact with opponents and the ball has gone to the ground, players may bind themselves into a ruck. There must be at least three players bound. The ruck ends when the ball leaves the ruck and can be handled by a player who is not part of the ruck, or when a scrum is ordered. A ruck is similar to a maul, except that the ball is on the ground. A player may use his/her hands to play the ball while it is in a ruck – doing so results in a penalty for the opposition.