No, it would not be enough, and I don’t only say this because the police shouldn’t exist in the first place. What’s more important is that they have a right to a fair trial just like anyone else. If there are literally any options to stop him from doing harm without killing him, they first need to be taken. And given that he was in his sister’s arms (it’s unclear if it was his sister or aunt to my reading, given that “the deceased” now refers to two of them) and not, yknow, holding the funeral goers hostage, there were still options.