Fortress (1986 cable movie) From IMDB review: A young teacher (Rachel Ward), preparing for a well-deserved hiatus, and her small class of nine students are kidnapped by masked gunmen and taken to the Australian Outback. They must band together to fight back and escape and discover that they have far more power than they could imagine.
TRIVIA: The film is loosely based on the 1972 Faraday School kidnapping of a teacher and her class by Edwin John Eastwood and Robert Clyde Boland. Eastwood later escaped from prison and repeated the crime with another teacher and her class in 1977.
Here's the movie trailer: http://www.youtube.com/watch?v=5FAB_mM5ttU