Dark Horizon (2007)

Tyler is convinced by his girlfriend Sarah to take her on a camping trip with Tyler's stepfather and stepbrother Chase to try and renew the familial bonds. With tensions already running high between the estranged stepbrothers, the feuding is exacerbated by unusual sounds and strange news reports. Gun-toting subversives stumble across the campsite and take out their aggressions on the unsuspecting campers. Now cut off from everything they know and fleeing for their lives, Tyler and Chase must rely on each other to try and save their loved ones, themselves and to find civilization.