“The pictures of airplanes flying into buildings, fires burning, huge structures collapsing, have filled us with disbelief, terrible sadness, and a quiet, unyielding anger. These acts of mass murder were intended to frighten our nation into chaos and retreat. But they have failed; our country is strong.” — former President George W. Bush

Sunday marks the 15th anniversary of the tragic events of Sept. 11, 2001, when our country fell victim to al-Qaida and triggered our initiatives to combat terrorism. More than 3,000 people were killed that awful day (including more than 400 police officers and firefighters) in New York City and Washington, D.C. Vicious terrorists flew two planes into the towers of the World Trade Center in lower Manhattan, a third plane hit the Pentagon just outside Washington, D.C., and the fourth plane crashed in a field in Pennsylvania after a brave group of citizens tried to wrest control from terrorist extremists.

Scroll through the gallery to remember Sept. 11, 2001.

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