One of the scariest scenes ever

I don't know if this has been talked about already, but the first few scenes of the movie are really very scary. In particular, I'm talking about the scene where the brother and sister are having a casual conversation and going down a normal highway road, with the nice row of houses, and they just glance to their side and see someone dumping something wrapped in sheets with blood on them, down a chute. And when they stare at him, he stops what he is doing, and.....just looks at them. I don't know for some reason this scene really creeps me out, more so than any gory scene in the movie. Maybe because it seems like such a real possibilty- you are driving down a highway, and you casually glance and see something that has horrific implications.