The bombs that hurt so many near the finish line of the Boston Marathon on Monday were made from 6 liter pressure cookers filled with metal and ball bearings and hidden in black duffel bags.
The use of a pressure cooker as an improvised bomb is the type of technique that is taught in Afghan terrorist training camps, according to a 2003 bulletin by the Department of Homeland Security (DHS).
“Pressure cooker bombs are made with readily available materials and can be as simple or as complex as the builder decides,” according to the DHS bulletin. “These types of devices can be (detonated) using simple electronic components including, but not limited to, digital watches, garage door openers, cellphones or pagers.”
The memo also warns that given the familiar appearance of the pressure cooker it is “often overlooked when searching vehicles, residences or merchandise crossing the U.S. Borders.”
Investigators have not found any evidence that this bombing is linked to foreign or al Qaeda connections. “We really don’t know if it’s a foreign or domestic threat,” said Rep. Michael McCaul, R-Texas, chairman of the House Homeland Security Committee. “We don’t know whether this was a homegrown terrorist or part of a wider conspiracy.”
A pressure cooker speeds cooking by creating a tight seal and building pressure inside the pot with internal steam pressure from the boiling liquid causes saturated steam (or “wet steam”). Converting it into a bomb covers the explosive material in a metal casing, that will blow apart when the bomb is detonated and adds to the explosive already packed inside.
Instructions on how to make a pressure cooker bomb similar to those used in the Boston bombing were published two years ago in Inspire, an online magazine which is tied to al-Qaeda.
The article, “How to Make a Bomb in the Kitchen of Your Mom,” by “the AQ Chef” instructed would-be bombers to glue shrapnel to the inside of a pressure cooker and then “fill in the cooker with the inflammable material.” It also states to use gloves to prevent any fingerprints from being found on the bomb fragments.
Investigators found a circuit board that they think may have triggered the bomb, according to the Boston Globe. While it was thought at first that the Boston bombs were detonated by cell phones, they were actually done by timer devices, law enforcement officials stated.
“This will be a worldwide investigation,” FBI Special Agent Richard Deslauriers said Tuesday. “We will go to the ends of the Earth to identify the subject or subjects who are responsible for this despicable crime, and we will do everything we can to bring them to justice.”
“Our mission is clear: to bring to justice those responsible. The American public wants answers. The citizens of the city of Boston and the Commonwealth of Massachusetts want and deserve answers.”
Three people were killed and more than 170 others were injured, 17 of them critically, in a pair of explosions near the finish line of the Boston Marathon Monday afternoon. No suspects have been identified.
Boston Marathon Bombing Result of Pressure Cooker Bomb
In a major breakthrough, federal investigators have recovered the mangled remains of one of the bombs planted along the route of the Boston Marathon Monday, according to two counter-terrorism officials briefed on the case.
The officials told ABC News the remains show a medium-sized pressure cooker, packed with wires, a circuit board, nails and ball bearings.
Pressure Cooker Bomb Hid in Black Bags Caused Boston Marathon Explosion
The explosives used in the deadly Boston Marathon bombing were contained in 6-liter pressure cookers and hidden in black duffel bags on the ground, a person briefed on the investigation told The Associated Press on Tuesday.
One of the explosives contained shards of metal and ball bearings, and another contained nails, the person said. A second person briefed on the investigation confirmed that at least one of the explosives was made out of a pressure cooker.
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