Scores of dead geese rained down from the sky during a “freak event” in the US.

The birds were migrating north over Idaho when the entire flock was struck by lightning, wildlife experts say.

More than 100 plummeted onto a car park and nearby rooftop in the city of Idaho Falls during a ferocious storm. Their bodies were left soaked by the rain and pummelled by hailstone the size of golf balls.

“All of them were dead,” said James Brower, coordinator with the state's Department of Fish and Game. “When the officer arrived, nothing was moving or twitching. Mother nature is sometimes cruel to the wildlife kingdom.

“We worry about accidents with cars and trucks - sometimes animals are affected just by the weather.

Officials initially found 51 birds on the ground on Saturday but a further 61 were later discovered on the roof of a nearby warehouse. They were a mix of snow geese and ross geese.

Mr Brower said that IDFG officer Jacob Berl was one of the first on the scene. “He opened a few up and saw their lungs were exploded,” he said. “It’s sad. It’s never something you want to see.”

It is thought a perfect storm of factors - the timing, wind and direction of flight - all contributed to the deadly incident. However, in order to better understand how precisely the lightening affected the flock, the department has said it will now send several of the birds for necropsies to determine an official cause of death.