Updated Wed., April 17, 10:55 am
One of the bombs that exploded near the Boston Marathon finish line was composed of explosives and shrapnel packed into a pressure cooker that was hidden in a black nylon bag, according to authorities. The second device was also in a metal container but authorities have not been able to determine whether it was a pressure cooker or not, the FBI and Dept. of Homeland Security said in a statement.
The devices were put inside the bags and appear to have been carried to the route and placed near the Boston Marathon grandstand, where investigators believe they were detonated using a timer.
Investigators told NBC News that the two bombs included BBs, ball bearings, and tiny nails.
A document released by the FBI and Department of Homeland Security Tuesday said that pressure cooker bombs are very common in Southwest Asia, including parts of India and Pakistan. Inspire, an al-Qaida magazine, has also referenced pressure cooker bombs, as has William Powell’s The Anarchist Cookbook, according to the FBI.
Pressure cooker bombs were previously used on American soil in an attempted 2010 attack on Times Square that was thwarted by street vendors. In that case, the FBI said one of the pressure cooker bombs was packed with firecrackers.
In 2012, PFC Naser Jason Abdo was sentenced to two consecutive life sentences, plus 60 years, in prison for being in possession of bomb-making materials, including two pressure cookers.









