What happens if a hit ball hits the umpire standing behind the pitcher?

The ball is in play like any other batted ball and is considered fair whether or not it ricochets into foul territory after hitting the pitcher.

If the ball hits the pitcher on the fly and is caught by a fielder before it touches the ground, the batter is out. If a ground ball touches a pitcher and another fielder grabs it and throws the batter out at first base, the pitcher is given an assist on the putout.