Bombs at the Boston Marathon

Yesterday two bombs were exploded at the finish line of the Boston Marathon. The clock time when the bombs went off was about 4 hours. It's a sad day. Watching the videos of the bombing and hearing the reports makes me want to cry. I don't understand why people have such little respect for human life. It's obvious to me that the massacre was planned to maximize the civilian deaths. I hope the police can identify the people responsible for the bombing.