The Neibaur siblings Eric (15) and Lauren (13): Facebook / Eric Neibaur

An emergency response volunteer went into cardiac arrest while helping to remove bodies from the scene of a “horrific” car accident in which two teenage siblings and a 70-year-old man were killed.

Eric Neibaur, 15, and his 13-year-old sister Lauren Neibaur died when their pick-up truck collided with Jay Lanningham’s vehicle on a major road in the US state of Idaho.

Police said a member of the local search and rescue unit had to be revived with a portable defibrillator after his heart stopped at the scene of the crash, reported the Idaho State Journal.

The emergency responder spent three nights in hospital but was discharged on Wednesday.

Local sheriff Lorin Nielsen told the newspaper the difference between this accident and others he had dealt with was that “the damage was so horrific and there weren’t any skid marks.”

“All of us have seen death before, but when we have kids that are about the same age it really hits home a bit more than anything else does,” he said.

Eric and Lauren were driving a short way behind their mother and stepfather on Sunday – Father's Day – after spending the weekend camping and riding dirt bikes together, according to the Journal.

The teenagers’ parents were checking on them in their rear view mirrors, but realised there was a problem when they lost sight of the siblings’ red Chevrolet truck.

The third victim of the crash, Mr Lanningham, was with a young female passenger who suffered serious injuries and was airlifted to hospital where she was said to be in a critical condition, but expected to survive.

The siblings' father, also called Eric Neibaur, said the pair had "loved to torture each other" but had also "loved each other very much".