First Hologram

I have watched the movie a couple of times, but one thing escapes me. In the first hologram images, we see the Engineers running through the group, with one lagging behind and falling. They follow the images and only see the lagging Engineer fall, and get decapitated. Since this is all that was seen, do we know the first Engineers made it inside, or did they continue down the tunnel, and is this the pile of dead Engineers that the two crew members ran across before their demise. It is probably not important, but it made me wonder about the dead pile of Engineers. I tried to remember how many Engineers were running, and tried to get a count of how many bodies were piled up, but never got a good long look to get a count. If my thought on this is bogus I apologize, but I feel something is missing there, and I do not know why. I have not seen a thread about this so hope it is not a duplicate. Thanks.