method in the madness

God, the more you read about it, the worse it gets. Those poor people.
What I find particularly chilling is how the terrorists built the building itself into the weapon:

Security forces alleged the attack had been meticulously planned days before pupils returned to school on Wednesday after the summer break.
"We found a large amount of explosives and mines and their number says that this attack was planned in advance," the top local security official for the southern Russian region, Valery Andreyev, said.
"The armaments were hidden on the school grounds."
Another official said the militants has posed as builders in July, and snuck in bombs, mines, rocket launchers along with other weapons disguised as construction material.

That methodology is so al-Qaeda, they're sure to be involved in some way.
It's a really sinister idea to think a building can be taken in such a way. Makes you hope our intelligence agencies are going over possible targets at home with a fine tooth comb.