An enormous mushroom cloud formed in the sky over Beijing late last week, sparking fears that a cataclysmic, Armageddon-like event was underway.

Alas, it was not the end of the world—or worse, the beginning of a real-life movie starring Will Smith: It was just nature.

The giant cumulonimbus—which spanned several miles—was accompanied by lightning, swallowing up the capital's skyline for an hour, according to the Daily Mail.

Photographers and videographers captured images of Thursday's ominous-looking formation, which "gradually took the shape of an explosion from an atomic bomb."

According to the National Center for Atmospheric Research, a giant cumulonimbus is a thunderstorm cloud that forms from a towering cumulus, which "resembles the head of a cauliflower."

Here's some video of the cloud over Beijing: