From a CNN article about the Prague shooting:

Jakob Weizman, a Danish student at the Charles University in Prague, was taking an exam on Thursday when he started hearing gunshots and screams.

His first instinct was shock, he said - he never thought a school shooting would happen near him, in Europe.

“I lived in the US for a very long time, if it would happen anywhere, it would have happened in the US,” he told CNN afterward. “Now it’s spreading like a disease to Europe as well.”

He pointed to a recent spate of shootings elsewhere in the continent, saying: “You see this happen in Denmark, Serbia, and now here. This is incredibly frightening, you know?”

Maybe, courtesy of social media and instant communication worldwide, the gun madness here is infecting the rest of the world. Or violence anywhere infects everywhere.