http://www.usatoday.com/story/news/nation/2013/04/16/boston-marathon-explosions/2086853/
Still it's a security failure regardless of how you slice it.
BOSTON — The explosive devices that killed three people and injured scores at the Boston Marathon finish line were made from pressure cookers filled with metal and ball bearings and left in a backpack, according to a federal law enforcement official.
"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 bulletin noted that cooker bombs were used in an attack on an airport in Nepal in 2002 and a foiled attack in India in 2003.
Still it's a security failure regardless of how you slice it.