Layne was umpiring at first base with a man on first when Pena drilled a hard foul ball directly at him, forcing Layne to make an acrobatic jump to try and evade the ball. The ball struck Layne in his lower leg and knocked him off his feet.
The Rockies' training staff came out to help Layne, and a cart was called to take him off the field, but Layne was ultimately able to walk off the field on his own.
Layne was taken to Denver's Rose Medical Center for tests.
The game continued with a three-man umpiring team while Layne received treatment inside. Pena struck out for the inning's first out, and after Alfonso Soriano singled to left to put runners on first and second, Tyler Colvin grounded into an inning-ending double play.
Owen Perkins is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.