Regardless of what someone looks like or what their name is, if you see them at a school with a device like this and it's beeping, I think it's reasonable to call the police. Allow them to come and have someone with expertise ensure that it isn't a bomb and determine the student's intention. Hopefully the police that arrive do their job well - with diligence, compassion, professionalism, and without animosity or bias.
Police were called, he was detained and questioned, and then released without charges [2]. It's a tragedy that we see bombings and shootings in schools - but we do see them, and far too often. These are the times we live in. So how should this have been handled?
Hopefully Ahmed doesn't lose any passion for science or electronics because of this afternoon, but I think if people handle the situation with rational thought rather than instigation, then he will have a much better chance at that.
1. http://www.wired.com/2015/09/heres-bomb-clock-got-ahmed-moha... 2. http://www.washingtonpost.com/news/morning-mix/wp/2015/09/16...