I assume it was to secure the place first? Did he shoot for 72 minutes or around 15 minutes? Because if he stopped after 15 minutes then what difference does it make if it took them 72 minutes. Noway they could have reached him within 10/15 minutes.
either way when something like this happens you’re on your own. Don’t depend on someone coming to rescue you or stop the madman.
He “shot down the hall at a security guard” according to the scanner.
The believed it was two shooters with fully automatic weapons.
I imagine they waited for SWAT after a few LEOs got shot and killed.