Dark Floors (2008) on Netflix

While in the hospital for a tomography of the brain of his autistic daughter Sarah, Ben becomes upset when there is a power failure. He decides to leave the hospital with Sarah, while the nurse Emily tries to convince him to leave Sarah for further treatment. They get the elevator with three other passengers, and suddenly the elevator stops; when the door opens, people has vanished from the hospital, the environment is creepy and they are chased by devilish monsters. They find that they are trapped in the hospital, and the creatures seem to be hunting Sarah.