The Boston Marathon bombs that killed three and injured more than 175 appear to have been assembled from household pressure cookers, a crude but effective explosive that has been thwarted before in U.S. terror plots, the Wall Street Journal reports. Investigators are exploring whether the bombs were assembled not far from the scene of Monday’s horrific explosions since transporting such improvised devices over any significant distance could trigger a premature detonation.
U.S. counterterrorism officials have warned for a decade about the use of pressure cookers to manufacture bombs. The warnings came after finding such bomb-making was being taught at terrorist camps in Afghanistan. In 2010, the Yemen-based al Qaeda in the Arabian Peninsula’s Internet magazine published a step-by-step guide that included the use of a pressure cooker. The article, headlined “Make a Bomb in the Kitchen of Your Mom,” listed common items including filaments from Christmas light bulbs, gunpowder and a clock. The idea was to avoid buying chemicals and explosive precursors that are tracked by authorities “so as not to arouse suspicion.”