Videos of a mushroom cloud over Beijing on Monday have the Internet freaked out as concerns rise about just what caused the odd atmospheric phenomenon.

The Internet exploded in a furor of speculation about the cloud, which rose over the skyline of Beijing, China, in what can only be described as a mushroom-cloud-like formation.

No verifiable account of what could have caused the unusual display has been offered, though many people have offered their two cents, from guessing that it is a result of aliens or heavy smog in the massive city, or that it could just be a coincidental, but normal, cloud formation.

Many other observers also found the formation beautiful, and called it everything from amazing to astounding in online comments.

Chinese authorities told residents of Beijing to stay inside on Monday on account of the green, yellow and orange mushroom cloud, according to Agence France-Presse, and many residents have expressed shock that a formation so similar to that of the aftereffects of an atomic bomb could appear over their city.

YouTube user ChroChaoChris sought to clear up the controversy by offering his own guess of what caused the so-called mushroom cloud:

This is just a Cumulonimbus (thunderstorm cloud) enlightened by the sun, he wrote in a comment on the YouTube video. It? happens everyday all over the world ! Can't believe people can be so ignorant about such a classic phenomenon.

YouTube user KickDownDoors offered a different take on the situation in his own comment on the video:

Wasn't China creating rain clouds weeks and days before the Beijing Olympic Games to clear the air of industrial pollution and smog? he wrote. I think this is something similar.

It is not the first time such a mushroom cloud has been reported hovering above a city. In 2011, residents of the city of Haarlem in the Netherlands took video and photographs of a similar cloud formation over their city and posted them online, prompting Internet reactions similar to the concerns now being voiced over the Beijing video.

The Beijing mushroom cloud video emerged on the tail of the emergence of frightening photos depicting clouds of smog that descended on Eastern China last week.

Click play below to watch the Beijing mushroom cloud video: