having spent time in ER's over the years for various stupid things. I can attest that it's one of the most stressful and potentioally violent places you have to go to. This story on Boston.com highlights what the nurses have to deal with. In a time of crisis you can expect many more people with shorter fuses.
I was in one for a broken wrist and watched a woman claim the hospital was "racist" because they took a white guy who cut off 4 fingers on a table saw before her kid with a case of the sniffles.
If you have to go to the ER be careful, don't go alone, and don't give the nurses a hard time, honey works better than vinegar.