I have watched many hours of news coverage, including the president blaming guns, and still haven't heard of any investigation of the padlocking of exits and trapping of the patrons inside. There are two sides to the three hour delay, people likely bled to death during this time; but on the other hand, there was a lot of talk about "suspicious" devices(bomb)in the beginning of the showdown. The correct reaction to an active shooter is an immediate assault, but when you add possible explosive devices, I wouldn't want to "sharp shoot" the decisions of those in charge.
Mike