The explosives were similar to those used in the Madrid attacks. Bomb disposal experts found between 24 pounds (10 and 12kg) of explosives connected to a detonator with a 440-foot (135-meter) cable.
On July 7, 2005, al Qaeda suicide bombers killed dozens on the London underground system. A follow-on attempt two weeks later failed when the bombs malfunctioned.
In December 2012, German police discovered a crude improvised explosive device placed in a bag on a platform at the main railway station in Bonn. German authorities have stated they have "robust evidence" Islamist extremists were involved but no arrests have yet been made.