I am not defending the Philadelphia PDs actions here, which were clearly inappropriate, but I don't think it's accurate to say they "murdered" 11 people. If the PD kills someone while trying to serve an arrest warrant after being shot at, that is pretty clearly a lawful homicide and not murder. The death of the children could certainly be considered manslaughter but I don't think it meets the standard for murder either since there was, arguably, no intention to kill them.