BOSTON, Mass. - Investigators say the explosives that went off at the Boston Marathon were in 6-liter pressure cookers inside black duffel bags on the ground.
Investigators say the explosives contained shards of metal, nails and ball bearings. Law Enforcement Officers have some of the bomb components, but do not yet know what set off the explosives.
Tuesday morning, President Barack Obama called the bombings an act of terrorism.
Investigators say at this point they don't know if the attacks were carried out by an international or domestic organization, or possibly a "malevolent individual."