Honestly and truthfully, this scenario scares the shit out of me from an LE perspective. Lon, you are not alone in your grasp for knowledge on this particular event. I'm at a loss as to how one would or for that matter, could respond other than direct action at the door as LVMPD did. As for LE capability, I think we'd be hard pressed to see any agency be able to effectively respond to this scenario from the ground. LE uses the term "designated marksman" as a title befitting of anybody capable of passing a lax 100 yard course of fire here in Ohio. Hardly what I'd consider skilled. True SRT/SWAT, in my opinion, is reserved for the likes of LAPD, Miami/Dade, NYPD, and FBI HRT. All other agencies are best attempts with the resources they have at the moment.
We are in trying times.