Apr 17, 2013
AMC - The bombs have been confirmed as having been made from at least one 16 Qt pressure cooker and loaded with BB's, ball bearings, and small nails. They believe, but have not confirmed that the explosive might have been black powder or a similar low yield type. No claim of responsibility has been made yet. This bothers me as it makes me think they are homegrown, possible American citizens.
See http://bostonherald.com/ for a good source of articles. Also see http://www.bostonglobe.com/ for the other Boston paper.