Now, more than a million viewers have watched the video, in which a hungry dinosaur chases terrified workers down hallways.
The video was uploaded to YouTube by a Japanese version of the U.S. TV show "Pranked," and also shows the reactions of people set up the prank.
In one clip, a man walks down an empty hallway. There isa scream, and then workers in the building run through a nearby hallway. Moments later, the Godzilla-sized velociraptor begins chasing a man. The man falls down, gets up, and continues running away from the prehistoric beast.
Several other workers run away, terrified. One woman realized it was a prank midway through, and said (in English), "Oh my God."
The account later posted the second part of the prank.