Metal Pressure Cooker Bombs Used in Boston Marathon Attack

Officials are working around the clock to investigate Monday’s bombings at the Boston Marathon. One person briefed on the Boston Marathon investigation told journalists that the bombs were placed in six-liter pressure cookers and then placed in black duffel bags. Dr. George Velmahos, chief of trauma surgery at Massachusetts General Hospital, says this type of bomb is consistent with the traumatic amputations experienced by many of the victims. 

Pressure cookers are sealed cooking vessels that do not permit air or liquids to escape below a pre-set pressure. They are used for cooking food quicker than conventional cooking methods, which saves energy. Pressure cookers heat food quickly because the steam pressure from the boiling liquid causes saturated steam (or "wet steam") to permeate and cook the food.

The person, who wishes to remain anonymous because the investigation is still ongoing, said the pressure cookers and duffel bags were filled with metal, nails, and ball bearings, and then placed on the ground. Law enforcement officials have several components of the bombs; however, it is still unclear what was used to ignite the explosives.

On Tuesday, President Obama said the bombings were an act of terrorism; however, it is still unknown whether an international or domestic organization or a “malevolent individual” carried out the bombings. 

Police and federal agents are seeking more information, and have appealed to the public for amateur video and photos that might yield clues in the bombing. Special Agent in Charge of the Boston FBI, Richard DesLauriers, vowed, "We will go to the ends of the Earth" to find whoever carried out this deadly attack. Picture and video can be submitted here: Boston@ic.fbi.gov.

The latest tally indicates that 170 people have been wounded and three have died, including an 8-year-old boy.