Residents of Tyumen in south central Russia went into an end-of–the-world panic when they saw a mushroom-shaped rising over their city. Pictures were immediately posted on the Internet and the rest of the world started googling “Armageddon.” “World War III” and “where to find radiation-proof toilet paper.” Did someone press the wrong button?

Tyumen was the first Russian settlement in Siberia back in 1586 and today is a major oil-and-gas center, so a nuclear attack on the city as a way to cripple Russia’s energy industry makes sense. Is that what Tymuen residents were thinking? Here’s a tweet from Oleg Alexeeva:

Oh, God save us. What have they done?!!!

Here’s another apocalyptic tweet:

Crazy b******s!!! This is the end.

Of course, some took a deep breath (even though that’s dangerous during a possible nuclear attack) before tweeting:

I think someone would have said something if we suddenly found ourselves under nuclear attack.

Good point. No one heard any explosions either, which eliminates a nuclear device as well as a conventional bomb or missile attack. Volcanoes can emit mushroom clouds but there are no volcanoes nearby. And there were no reports of meteors.

There are plenty of oil and gas facilities and storage depots in Tyumen where an explosion could cause a mushroom cloud, but nothing like that was reported by the media or local authorities. A large forest or brush fire could cause a mushroom cloud, but no occurrences of either were seen in the area.

If you’re an end-of-the-world type or a conspiracy fan, this is all pretty disappointing … unless you live in Tyumen. So, what exactly was this mushroom cloud they saw?

According to meteorologists, it was most likely an anvil or cumulonimbus incus cloud which had reached a stratospheric level that caused it to flatten out on the top. They can become supercells causing tornadoes or severe thunderstorms but the one over Tyumen didn’t look too threatening and there were no reports of storms.

Weather control test? You never know in Russia. Nuclear attack? Nope. But to be on the safe side, Tyumenites may want to stock up on lead umbrellas.