Cast: William Hopper (Col. Robert Calder); Joan Taylor (Marisa Leonardo); Thomas Browne Henry (Gen. A.D. McIntosh)); Frank Puglia (Dr. Leonardo); John Zaremba (Dr. Judson Uhl); Jan Arvan (Contino); Bart Bradley (Pepe); Tito Vuolo (Police Commissioner); George Khoury (Verrico, a fisherman); Don Orlando (Mondello, a fisherman); George Pelling (Maples, a reporter); Sid Cassel (Farmer-first victim); Arthur Space (Dr. Sharman)

Producer: Charles H. Schneer; Director: Nathan Juran; Screenplay: Bob Williams, Christopher Knopf (from a story by Charlotte Knight); Technical Effects: Ray Harryhausen; Art Director: Cary ODell; Directors Of Photography: Irving Lippman, Carlos Ventigmilia; Film Editor: Edwin Bryant, A.C.E.; Sound: Lambert Day; Set Decorator: Robert Preistley; Music Conducted by: Mischa Bakaleinikoff.