Horrible stories coming out of Paris.
But similar attacks in an African mall and in Mumbai suggest this might be the way to scare people. Of course in the long run it will not make you popular, but hey, its about terror not reality.
In the USA, usually it is crazies who do this, and an occastional "amok" attack in the Philippines, but here there are "terrorism" problems like the attack on Zamboanga that resulted in thousands fleeing from terrorists (but didn't get much publicity, even here, because the dirty little secret is that the attackers were local Moro/Mslims and those who fled were mainly Christians...and the gov't is trying to make nice to get a treaty in the south).
So how should you respond?
GTFO....get out as fast as you can
in the US, one response is to carry a gun, but as the article points out, you need training or you will freeze under stress (which is why I don't carry a gun). You need to be aware/street smart and constantly have a plan for self defense.
I used to have the street smarts as a student in the inner city, but nowadays I would be a sitting duck...
Training helps: This is not just true for these emergencies but also in CPR: You need to do such things automatically or you will freeze and not be able to think.