I thought you did a great job capturing the horror element of story, both from the perspective of the protagonist's initial PTSD experience in the moment, as well as the anguish that came later with the realization of what happened. It was a relatively short piece, but you managed to fit a lot of drama and action into just a few words, which really worked for the story.

I found the point of view shift between Bill's first person perspective to a third person objective point of view centered on Lieutenant Gannon to be pretty jarring, particularly since Gannon is describing the same character as the first-person POV in the earlier part of the story. A third person perspective centered on Bill, or Gannon's perspective without quite so much focus on Bill as a character might help smooth that out a little.

This story was definitely dark and horrifying; you did a great job of making sure that atmospheric genre element was infused throughout the piece.