Gas-s-s-s

Gas-s-s-s is a 1970 American post-apocalyptic black comedy film directed by Roger Corman, written by George Armitage, and produced and released by American International Pictures. The plot follows survivors of an accidental military gas leak involving an experimental agent that kills everyone on Earth over the age of 25. The subtitle alludes to the 1968 quote "it became necessary to destroy the town to save it" attributed to a U.S. Army officer after the Battle of Bến Tre in Vietnam.

Synopsis from Wikipedia, CC BY-SA 4.0. Everything below written here.

Poster © the film's rights holders.