Exclusive Interview Ex-President George W. Bush, Laura Bush

Boston Bombs Likely Built From Fireworks"Whether it be that or the explosion at West, Texas, I mean it harkened back to days where you become the comforter in chief ... try to help heal souls that are hurting," Bush said.

Exclusive Interview President George W. Bush, Laura Bush

When George W. Bush saw the news about Boston, his mind immediately turned to organized terrorism--and to his own presidency.With his presidential library opening Thursday at Southern Methodist University in Dallas, the former president spoke with ABC News' Diane Sawyer in an exclusive interview, detailing how he reacted to the bombs in Boston and the days-long manhunt that followed. The attacks, he said, reminded him of a time when it was his job to comfort the nation.

Bush's tenure in the White House was defined, in part, by that role, which he took on after the attacks of Sept. 11, 2001. The attacks on the World Trade Center and the Pentagon would launch the "Global War on Terror" his administration prosecuted for nearly eight years. They would also come to define how many Americans view terrorism.

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When he first heard about the Boston attacks, Bush said, he worried about an organized, coordinated terrorist plot.

"I was deeply concerned that there might've been an organized plot," Bush said of the Boston attacks. "I don't know all the facts. I don't think we all know all the facts. But I was deeply concerned that this could've been, you know, another highly organized attack on the country. And it still may be--again, I don't know all the facts."

Bush's presidency was also defined by the hunt for al Qaeda terrorists, and he praised law enforcement authorities for their response to the Boston attacks. After two bombs exploded at the Boston marathon last week, police apprehended suspect Dzokhar Tsarnaev Friday night.

"I do know that it's really hard to protect the homeland. I mean, those who want to do harm only have to be right one time, and we have to be right 100 percent of the time," Bush said. "I was extraordinarily pleased with the response. The local authorities, state authorities, and federal authorities did a really good job of finding at least the two guys involved."