Emergency crews have saved two people after their pick-up truck plunged off a bridge, leaving them dangling above a deep gorge in southern Idaho.

Idaho State Police responded to the accident on Monday, said ISP spokeswoman Lynn Hightower, and an officer found a man and a woman inside the truck dangling nose-down off the side of the bridge spanning the Malad Gorge.

The gorge is narrow but is roughly 100ft deep below the bridge, roughly the height of a 10-storey building. The gorge reaches about 250ft deep at its deepest point.

The only thing keeping the 2004 Ford pick-up from falling was a set of “safety chains” attaching a 30ft camper trailer, which remained on the bridge, to the pick-up.

A state trooper and local sheriff’s deputy first used an additional set of chains from a nearby lorry to help support the dangling truck, holding it in place until additional rescuers with cranes, rope rescue gear and other equipment could arrive.

Emergency crews were then able to rappel down to the hanging truck and attach a harness to each occupant, allowing them to be safely carried back to the bridge.

Both were taken to hospital but neither appeared to have life-threatening injuries, Ms Hightower said. Two small dogs inside the pick-up were also rescued and taken to the home of a nearby family member.

“It was terrifying,” Ms Hightower said. “It was definitely a heroic rescue from everybody that was out there, and thankfully, they’re all fine.”

Witnesses said the truck appeared to lose control before the crash, swerving to hit the right shoulder barrier before sliding over the left-side guardrail. The truck then tipped over the bridge, with the camper blocking both lanes of the bridge.

The case remains under investigation, Ms Hightower said. Agencies from Gooding, Jerome and Twin Falls responded to the incident, along with regional sheriff’s offices and fire department and paramedic services.

“A rescue like this takes a lot of quick thinking and action but this is what they train for,” she said. “That training just paid off today, and two people are alive because of the hours and hours of training that these emergency responders do.”