If they used a frag bomb, like a Claymore, I would be really disturbed. I would assume it was a breaching explosive which killed by blast overpressure or brisance.
If we are going to complain about the weapons that the police are allowed to use for self defense, then how can we complain when the police or the government tell the citizens what types of weapons they can use. Are the people here who are willing to tie the hands of local law enforcement on the weapons they can use willing to defer to others the decision on what kind of weapon they can use under similar situations?