Some time ago, I read about the “going postal” phenomenon. This thing refers to a series of murders that took place in the american postal offices. There were many incidents of postal workers that had killed their supervisor or some of their co-workers. The strange thing about this is that almost all of those murders had occurred by postal office employees. If you wanna know more about this strange phenomenon have a look at this article here: https://en.wikipedia.org/wiki/Going_postal .
There’s also an interesting documentary that deals with this issue. You can look at it here: