Standard procedure literally nationwide is that normal officers are expected to go in with what they have. That’s exactly what happened in Nashville less than a year later:
The body cam video is public. Officers responded with what they had. Yes, there’s an officer with an AR. There are also officers clearing rooms with handguns and in plainclothes. And one of the officers that engaged the AR-wielding shooter did so with their duty handgun.
Body Armor, AR15s.
They absolutely wear the former every day and many these days have either an AR or a shotgun in the trunk of their patrol vehicle.