18 years ago on Sep. 11, 2001, disaster struck the nation, converting the country of freedom and liberty into one of fear. 19 hijackers took over four planes, three of them crashing into three major government buildings, one falling into an empty field.

Here’s a timeline of the major events that took place on the horrific day:

7:49 a.m.: American Airlines Flight 11 takes off from Boston Logan Airport.

8:15 a.m.: United Flight 175 takes off from Boston Logan Airport.

8:20 a.m.: American Airlines Flight 77 takes off from Washington Dulles Airport.

8:41 a.m.: United Airlines Flight 93 takes off from Newark Airport. The flight was originally scheduled to depart at 8:00 a.m.

8:46 a.m.: Hijackers crash Flight 11 into floors 93-99 of the North Tower.

9:03 a.m.: Flight 175 strikes into the 75-85 floors of the South Tower.

9:37 a.m.: Flight 77 hits the western facade of the Pentagon.

9:59 a.m.: The South Tower collapses.

10:03 a.m.: Passengers aboard Flight 93 attempt to regain control of the plane from hijackers. The plane crashes into a field in Pennsylvania.

10:15 a.m.: The Pentagon’s E Ring collapses.

10:28 a.m.: The North Tower collapses.

Today, 9/11 represents a moment in American history that altered the country forever.