The April 19, 1995, Oklahoma City bombing stunned the nation, not only because of the horrific nature of the act itself but because no one thought that products as common as agricultural fertilizer and motor-racing fuel could be used to incinerate a federal building.

Six years later, the 9/11 terrorist attacks again sent the nation into shock at the idea that a group of people would commit a suicide attack by taking control of four planes and crashing them into multiple buildings.