Ok, first test, I had my sim call over sims to outside to talk until they got blue and one died, the whole mourning process caused the massacre, everyone ran outside to mourn, while mourning the next one died and so on and on until finally the mourning stopped and no one else froze. So that got me thinking what would happen if I don't call them outside. I am starting a whole new save game to test that theory. Here is the first one's pics .
https://i.imgur.com/zyreIym.png
https://i.imgur.com/0Go3d90.png
https://i.imgur.com/guqPGnh.png