I imagine that was done on some doors not all, just to better funnel people to the remaining open exits where they had their manned check points.

I cannot see that happening in the U.S. without armed confrontations.

Like guns or not, that's the 2nd Amendment at work.

Is it? Unless you have some sort of evidence that “they didn’t try this because guns,” that’s less than speculation.

That is ridiculous. I was commenting on a hypothetical situation.

People own guns for defense. There's reason to believe that if people are being trapped in a building against their will, they may use them.

Rather scary how massive apartment buildings in China, where most people live, are able to be turned into prisons so quickly.