8:45 a.m.

The first plane crashed into the north tower of the World Trade Center.

9:03 a.m.

The second airplane crashed into the south tower of the World Trade Center.

9:43 a.m.

The third airplane crashed into the Pentagon in Washington, D.C.

10:05 a.m.

The south tower of the World Trade Center collapsed.

10:10 a.m.

The fourth airplane crashed in a field in Somerset County, Pa.

10:28 a.m.

The north tower of the World Trade Center collapsed.