There are strange things happening throughout history of humankind, and they go down in history without any valid explanation why they occurred.
The Tunguska incident for instance. A huge and bright light was seen barreling down from the sky on June 30th 1908. It caused massive explosion on the eastern side of Siberia. The explosion was so horrific, it had a force two-thousand times more powerful than the bomb of Hiroshima and annihilated more than 2.000 square kilometers of forest and wilderness. And yet, nobody knows what caused the incident.
I know what you’re thinking. An asteroid or meteorite that hit the earth, right? I’m sorry but you’re wrong. It was highly theorized as so but there were no craters on the ground or any other evidence that supported this theory. The theory of the explosion of an underground nuclear bomb testing was also most unlikely to have happened. During that era, the Russians were incapable of such military firepower just yet. There were even theories saying that the explosion was caused by uncontrolled experiment of Nikola Tesla.
No human death was recorded since the area was not populated yet.