You dont hear about it. The people who killed in self defence are then killed by the backup.

https://www.nbcwashington.com/news/local/father-shot-2-officers-who-mistakenly-served-warrant-at-his-home/54589/

Here's one example although the cops lived. I do recall at least one or two other stories but can't find them on Google and wouldn't be surprised to learn they were buried intentionally. I thought one was in CO or somewhere in the Midwest from several years ago where a man shot a few cops who were at the wrong address.