C.H.U.D / 1984 movie

Photographer George Cooper (John Heard) is documenting the lives of subterranean homeless people, a population that has mysteriously dwindled. After receiving information from a reporter, George becomes aware of a conspiracy theory about cannibalistic monsters lurking in the sewers. He teams up with the reporter, a policeman (Christopher Curry) and a priest (Daniel Stern) to fight two battles: one against the cannibals and the other against a corrupt government official.