BOISE, Idaho—Authorities say a set of camp trailer safety chains and quick, careful work by emergency crews saved two people after their pickup truck plunged off a bridge, leaving them dangling above a deep gorge in southern Idaho. Idaho State Police responded to the accident at about 2:45 p.m. Monday, said ISP spokeswoman Lynn Hightower. A trooper found a man and a woman inside the pickup truck that was dangling, nose-down, off the side of the bridge spanning the Malad Gorge. The gorge is narrow but is roughly 100 feet deep below the bridge, roughly the height of a 10-story building. The gorge reaches about 250 feet deep at its deepest point. The only thing keeping the 2004 Ford F-350 pickup from falling was the set of “safety chains” attaching the 30-foot camper trailer, which remained on the bridge, to the pickup. A state trooper and local sheriff’s deputy first …