After the Sept. 11, 2001, terrorist attacks, heart-wrenching images surfaced and stirred the world.
Photos released by the US National Archives in 2016 show exactly when President George W. Bush learned the US was under attack.
See how Bush responded to what would be the defining moment of his presidency.
President George W. Bush participates in a reading demonstration on the morning of Tuesday, September 11, 2001, at Emma E. Booker Elementary School in Sarasota, Florida.
Dan Bartlett, deputy assistant to the president, points to news footage of the attacks while President Bush listens to new security information.
Bush watches television coverage of the attacks on the World Trade Center during a briefing in the classroom.
Bush takes notes as he listens to news coverage of the World Trade Center terrorist attacks.
Bush calls New York Gov. George Pataki, FBI Director Robert Mueller, and Vice President Dick Cheney. White House Chief of Staff Andy Card talks on a cellphone.
Bush delivers one of his first remarks to the nation after the attacks, from the elementary school.
A highway sign on Tuesday, September 11, 2001.
Bush watches television coverage of the terrorist attacks on the World Trade Center from his office aboard Air Force One.
Bush confers with White House Chief of Staff Andy Card in the president's stateroom.
Bush talks with his staff by telephone from his office aboard Air Force One, during the flight from Sarasota to Barksdale Air Force Base in Louisiana.
Bush talks on the telephone as senior staff huddle in his office.
Bush and his staff look out the windows of Air Force One at their F-16 escort while en route to Barksdale Air Force Base.
An F-16 escorts Air Force One.
Bush confers with, from left, Karl Rove, Andy Card, Dan Bartlett, and Ari Fleischer before delivering remarks on the World Trade Center disaster from the General Dougherty Conference Center at Barksdale Air Force Base.
Bush delivers remarks on the terrorist attacks before departing for Offutt Air Force Base in Nebraska.
Bush arrives at Offutt Air Force Base.
Bush, Admiral Richard Mies, left, and White House Chief of Staff Andy Card conduct a video teleconference at Offutt Air Force Base.
Bush and White House counsel Harriet Miers aboard Air Force One.
Bush speaks with Ari Fleischer, left, and Karl Rove aboard Air Force One during the flight to Andrews Air Force Base.
After departing Offutt Air Force Base for Washington, DC, Bush talks on the phone with Vice President Dick Cheney from Air Force One.
National Security Adviser Condoleezza Rice waits at the South Portico for Bush to arrive at the White House.
Counselor Karen Hughes and counsel Alberto Gonzales follow Bush into the Oval Office after his return to the White House.
Working with his senior staff, Bush reviews the speech that he will deliver to the nation in the evening.
Bush talks with Vice President Dick Cheney in the President's Emergency Operations Center.
Laura Bush listens as her husband discusses the terrorist attacks with White House staff in the President's Emergency Operations Center.
Bush and Laura talk with Vice President Dick Cheney and National Security Adviser Condoleezza Rice in the President's Emergency Operations Center.
After returning to the White House, Bush meets with, from left, Vice President Dick Cheney, Chief of Staff Andy Card, National Security Adviser Condoleezza Rice, and Special Agent Carl Truscott of the US Secret Service, in the President's Emergency Operations Center.
Bush reviews notes with Karen Hughes before addressing the nation from the Oval Office.
Bush delivers his televised address.
After addressing the nation, Bush meets with his National Security Council in the President's Emergency Operations Center.
This article originally appeared on Business Insider. Follow @BusinessInsider on Twitter.
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