I have reasons to believe nothing about this story as having occurred. It takes elements of previous stories, both real and fictional, and reworks them into a more diabolical and sensational package. It is designed to play off the fears that many have about Boston.
I doubt this story ever took place, given the details which do not add up.
I believe this story to be a forgery, repeated twice at least now, copied and pasted from another thread.
It helps to read it aloud for the inconsistencies and issues to be a little clearer. It reads like bad fiction, and it lacks credibility.