3 cats died w/n 24 hrs, has anyone experienced this before?

I’m posting here because I’m honestly at a loss right now. Three of my cats suddenly died within almost 24 hours. Before they passed, the main symptom I noticed was excessive drooling with a very foul smell. Everything happened so fast that I barely had time to process what was going on. I still have two cats left, and thankfully they seem okay for now. They’re active, eating normally, and not showing any obvious symptoms, but I’m monitoring them closely. I’ve been reading similar posts here on Rayover, and I noticed that some people mentioned it could possibly be Parvo or another viral infection. Of course, I’m not assuming that’s the cause, but the situation has me worried, especially because of how sudden everything was. Any advice or shared experiences would mean a lot. Thank you.