The New York Times

The scary thing about this kind of horrendous attack is that they are impossible to predict and prevent. They require almost no planning or preparation. If the perpetrator is quiet on social media and stays away from organized groups, they can fly completely under the radar. Given the ease with which this kind of barbarism can be carried out, it is very lucky that there are so few events like it. Barbaric minds must be few and far between.
See: http://nyti.ms/29He4Yc Cross-posted from Facebook via IFTTT