Pressure cooker bombs suspected in blasts

Federal agents released new evidence Tuesday on the Boston bombing saying it was done with kitchen pressure cookers packed with explosives,

nails and other lethal shrapnel.

Inside a pressure cooker bomb.

Boston bombs made with disturbing ease

Packed with shrapnel, pressure cooker bombs are crudely made but designed to cause maximum carnage.

Anatomy of a pressure cooker bomb

A look at the type of bomb that may have been used in the terror attacks at the Boston Marathon