WASHINGTON (AP) — President Barack Obama and first lady Michelle Obama laid a wreath at the Pentagon, one of several observances marking the 11th anniversary of the Sept. 11, 2001, terrorist attacks.

Aided by a Marine honor guard, Obama place a white floral wreath on a metal stand above a concrete slab that said “Sept. 11, 2001 - 937 am.” A moment of silence began at precisely 9:37 a.m.

Obama stood with his arms folded and head bowed as a bugler played taps, then raised his hand to his heart as taps concluded.

In the afternoon, the president was to visit wounded soldiers and their families at Walter Reed National Military Medical Center.

Vice President Joe Biden flew to Pennsylvania to deliver remarks at the Flight 93 National Memorial Commemorative Service.