“The Department of Homeland Security has gone public with an admission that an exercise was planned months before the Boston Marathon bombings that involved backpacks being used to detonate explosives by rogue terrorists. According to the DHS documents acquired by the Boston Globe, the agents were planning on conducting training exercises centered around a fictitious terrorist group called ‘Free America Citizens’, a group that would plant backpacks full of explosives around Boston that the detectives would be forced to track down. Ultimately, of course, this ended up happening at the Boston Marathon itself with precise accuracy.”
http://www.storyleak.com/dhs-boston-training-drill-backpack-explosives/