Angels pinch hitter Jefry Marte was at the plate with two outs in the bottom of the ninth inning when he lost control of the bat on a follow-through. The bat slipped out of Marte's hands and struck Emmel in the head.
Emmel fell to his knees, and his head was bleeding profusely. He left the field with a towel held to his head.
The Angels said after the game that their training staff had stopped the bleeding and Emmel -- fully alert -- was being taken to a hospital for stitches.
"It's scary, no doubt," Angels manager Mike Scioscia told reporters.
The game was completed by the remaining three umpires, with Quinn Wolcott moving from third base to behind the plate.
The Associated Press contributed to this report.
Umpire bloody after taking bat to the head
Plate umpire Paul Emmel is struck in the head by the bat of Jefry Marte and has to be taken to the hospital for stitches.