Predatory Sparrow: Did hackers start this steel factory fire in Iran?

It's extremely rare for hackers, who operate in the digital world, to cause damage in the physical world.

But a cyber-attack on a steel maker in Iran two weeks ago is being seen as one of those significant and troubling moments.

A hacking group called Predatory Sparrow said it was behind the attack, which it said caused a serious fire, and released a video to back up its story.

The video appears to be CCTV footage of the incident, showing factory workers leaving part of the plant before a machine starts spewing molten steel. It ends with people pouring water on the fire with hoses.