I am trying to find a movie that I have been looking for since I first saw it in the 90s. It’s from late 80s to mid-90s. All I can remember is that a family is looking for a teenage girl, and they find her on a stretcher covered in a sheet inside a large building full of other humans covered in sheets on stretchers. There is also a scene where people are trying to escape in a car, and there are tiny aliens in the back seat trying to attack them. The little aliens apparently can live inside the humans? This was a serious horror film and not a comedy/family type of movie.