CBS News has a wonderful slideshow made up of 120 photos taken at a haunted house. (see Terrified reactions at haunted house, Pt. 3) They write:
Much like snowflakes, no two people seem to react to a good scare the same way. Nightmares Fear Factory in Niagara Falls, Canada, illustrates this point by taking a picture of people at a particularly terrifying moment in their haunted house. It is unknown what exactly they're looking at - but it's obviously pretty scary.
Here are three samples:
Upon further investigation, we now know what these people were looking at. These folks actually were not in the huanted house. The were waiting in line to enter. Someone had left on a big screeen TV at the entry and they were watching this: