We have had several instances with a tactical unit officer (full time tac unit) NDing. One, a slung but not safed carbine discharged when the officer went hands on with a subject. Fortunately no one was struck. Another officer nearly ventilated a range officer behind the firing line with a weapon he believed clear. A third shot another team member on approach to a structure. The team member struck survived but had to undergo several surgeries.
I am not on any of these units, and I am not in a position to tell them how they should run their units. The really galling thing is that all the officers kept their positions on their respective teams.