Russian authorities have confirmed reports of a spike in radioactivity in the air over the Ural Mountains, but source of the "extremely high contamination" remains a mystery

Russian authorities have confirmed reports of a spike in radioactivity in the air over the Ural Mountains, but source of the "extremely high contamination" remains a mystery: https://t.co/Fm5upwlqWC pic.twitter.com/XRLvbVfTF0

— CBS News (@CBSNews) November 21, 2017