this tunnel vision/blood flow can occur with witnesses too(even the confusion part which can lead witnesses to not remember physical features of assailants, robbers, and so-on because they aren't pre-trained to notice these important details).
Often times they see one event and have no clue of what else is going on around them.
as for private ryan movie post, I think that is more of a shell shock scene as well as obvious side-effects to include physical amongst others of weapons w/regards to military warfare in close proximity (same actor from the movie "HEAT" in 1995)
"Damn the torpedoes, full speed ahead!" -Admiral Farragut @ Battle of Mobile Bay 05AUG1864