Charlie hebdo shooting
During an emergent situation, rumors can have social and psychological consequences.
“Horror struck Sweden at its heart today," Paris Mayor Anne Hidalgo says.
There have been 10 notable incidents since January 2015.
Joachim Roncin had no idea that the message he tweeted would become a slogan the entire world would pick up.
The satirical paper's director wrote that he wanted to "bash the heads in of those who dreamed of our deaths."