Oops. Looks like it may have been a sabotaged drill, or some imbecile who used live ordinance where a bomb was supposed to be a dummy.Tweeted by the Boston Globe 2 hours before the tragedy:https://mobile.twitter.com/BostonGlobe/status/323886829596205056
Just my opinion, but I doubt this was a coordinated attack. It was a single culprit who found a bomb recipe on the Internet. As to their motivation? What's the motivation for most of the nut jobs in the US who carry out heinous acts these days?