I think that is the mentality they need. I rather have a dead criminal than a dead police officer. Unfortunately, mistakes will always happen, so this OP piece, while unfortunately, will continue to happen. This time it happened to be a baby, which makes matters a lot more terrible for all involved.
Last year 44 police officers were killed violently[1] in the line of duty, and over 400 innocent people were mistakenly killed by the police. I'm not going to complain much about the police shooting violent criminals, but we're well past the stage of worrying about that.
[1] EDIT: Many more are killed in vehicular accidents.