So all I remember is two twin sisters are on this little ride in an amusement park and one of the sisters gets grabbed and disappears. The other sister has no idea what is going on and is freaking out. The ride stops and she sees a doctor cutting open her sister. It was gruesome. The amusement park got shut down and was abandoned for years. The next thing I remember is a group of teenagers break into the abandoned amusement park and crazy stuff starts happening. I believe they slowly begin dying off one by one in the movie. I watched it years ago but cannot remember the title of the movie. Please help! Thanks.