Want to Remember a name of movie

I watched a movie a long time ago, a year ago I guess, on HBO or WarnerBros TV channel. It was an old movie. Its plot was based on the after effects of Nuclear Test in somewhere in America. Some friends or family were travelling in an Van or moterhome, when some black thin people who were living In small caves or holes haunted them or hunted them. I cant seem to remember name of the movie