What one has to ask is why do such people become so wicked to that extent? What happens to their human hearts? These young people have siblings, parents and relatives however, they are willing to takes lives without compunction.
Only dehumanized hearts would do such a horrible act. No person in his/her right mind would work into a mall packed with shopping families and start shooting. The radicalization of young Muslim men in the west is something that has to be addressed properly. The mainstream western populations point fingers at the radical groups, however, we have to understand that these young men are handed to or forced to seek supposed 'purpose,' sense of self and human validation among the heartless radicals.
These young people live at the periphery of the society and that makes them easy targets of radical groups among whom they find a sense of belonging. The consequences of marginalization of these young people become the horror and a problem to the innocent civilians.