Perhaps the order came from very high up. Once an action has started that has possibilities of being pretty major, perhaps at the federal level it was decided that there was political gain to be had by a really massive slaughter. That is not “false flag” but it would be a passive equivalent.
Again, WHO gave the order NOT to intervene in an ACTIVE shooter situation?
At the rate that this perp was shooting people like fish in a barrel, WHO gave the order to hold back?
In this type of situation, the only objective is to neutralize the threat, and minimize the damage done. In this situation, there will be casualties. The objective is to neutralize the threat with the minimum.
It means the difference between 5 dead, and 50 dead.