I remember reading somewhere or hearing it from someone, possibly Ron Paul, that FEMA can actually take over the country completely as a backdoor towards martial law. FEMA can suspend local public emergency medical services or take them over as they see fit in such situations and therefore deny access to them to others based on their view of priority cases/situations.
There is a nugget of almost-fact here, but before I get to it, an anecdote.
I dearly love knowing that there are people out there who buy into the FEMA Shadow Government and Concentration Camp Traveling Funtime Jamboree. I like knowing that there's that kind of clueless credulity. I like it because when I'm doing something that I expect will bring me around these people, I plan ahead. Instead of my trusty laptop bag, I take my backpack. The one with FEMA's logo on it, and a nice little window to show off my FEMA identification. Makes 'em a little nervous, right into apoplexy once or twice. Entertains the heck out of me.
FEMA has no such power, but another Federal agency does - the Centers for Disease Control and Prevention. And there is no "take over as a backdoor towards martial law" nonsense. CDC can flat-out declare martial law and take control of any significant medical resources in an area facing an existential health and safety crisis. We're talking full-on Outbreak
-type stuff here. In such an event, yes, extremely precious medical resources are going to be expended on a priority basis. A triage system will go into place immediately, and in this kind of situation, you'd see some victims given black tags - palliative care only, because there ain't no saving them, and the resources are better spent on those with a greater likelihood of survival.
As to the matter of a citizen volunteer force, and its utility in two wildly different situations as discussed upthread, I can speak to why such a thing is good for the natural (or man-made) disaster recovery effort but not nearly so much for a ongoing criminal event later. It's been a lousy week at the day job and I need to take a sleeping pill and try to get enough rest to power through tomorrow.