C.H.U.D (1984)

They're not staying down there anymore!

A model and a photographer are abducted into a subterranean chamber of horrors beneath the streets of New York City. Inhabited by a collection of man-eating ghouls, this terrifying micro-society is dubbed, appropriately, "Cannibalistic Humanoid Underground Dwelling." As the creatures emerge from New York's sewer and subway system in search of fresh victims, the situation takes on a truly sinister dimension when the involvement of the United States Government is revealed.