Specially someone who was at Utoya in Norway.
The piece is interesting because of the level of denial, it can't happen here, "this is the safest spot in Norway", and just killing people like that isn't rational.
It's also interesting that the counselors had an hour's warning that something was wrong, notably the bombings beforehand.
There's also the mixture of tedium and terror that came with the people hiding. And then there's that the little voice of denial was still going strong even when the attacker was trying to shoot his way into the building.
And there's the valid point of, "you don't know what you'll do until your there."
Which leads to this gem:
The truth is that you really don't know what you'll do until you're there. What will you do if a guy with a knife suddenly bursts into the room as you're reading this? Did you have a plan before you finished reading the last sentence? Of course you didn't. Most people don't have a plan for reacting to a lunatic with a knife interrupting their morning latte, and, honestly, it would be pretty suspicious if you did.