Demons 2 (L'Incubo Ritorna) [1986]

Set during one long night in a 10-story, high-rise apartment complex in a nameless German city, Demons 2 begins with a film-within-a-film shown on TV about a group of four teenagers who investigate a "forbidden zone", in which a demon infestation once took place (see Dèmoni). Finding the lifeless corpse of a demon, one of the teens accidentally causes it to revive by its own blood. Sally Day (Coralina Cataldi-Tassoni), a teenage girl celebrating her 16th birthday party while her parents are out, is watching the broadcast when the demon on television somehow notices her and breaks out of the screen to attack her. Now a demon herself, she attacks and infects the partygoers, and the outbreak begins.(IMDB)