NEW YORK (AP) — Six moments of silence are part of the 9/11 anniversary commemoration.

The public is invited to observe any or all of them on Thursday.

Here is the list:

— 8:46 a.m. eastern time: Hijackers crash Flight 11 into the north tower.

— 9:03 a.m.: Hijackers crash United Airlines Flight 175 into the south tower.

— 9:37 a.m.: Hijackers crash American Airlines Flight 77 into the Pentagon.

— 9:59 a.m.: The south tower collapses.

— 10:03 a.m.: Passengers launch a counterattack on hijackers aboard United Airlines Flight 93. The hijackers crash the plane into an empty field near Shanksville, Pa.

— 10:28 a.m.: The north tower collapses.

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