In this file photo of Feb. 26, 1993, a New York City police officer leads a woman to safety following a bomb blast at the World Trade Center. Twenty years ago a group of terrorists blew up explosives ... more 
In this file photo of Feb. 26, 1993, a New York City police officer leads a woman to safety following a bomb blast at the World Trade Center. Twenty years ago a group of terrorists blew up explosives in an underground parking garage under one of the towers, killing six people and ushering in an era of terrorism on American soil. (AP Photo/Alex Brandon, File) less 
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Associated Press | Photo By Alex Brandon, File
Tue, Feb 26, 2013 8:55 AM EST