WASHINGTON ( CNN ) -- With moments of silence punctuated by somber music , readings of names , and tears , Americans held solemn memorial services Thursday to honor the victims of the September 11 , 2001 , terrorist attacks . President Bush comforts a mourner Thursday at the dedication of the Pentagon 's 9/11 memorial . Former Defense Secretary Donald Rumsfeld returned to the Pentagon to help dedicate a memorial to victims of the attack there . `` Today we renew our vows to never forget how this long struggle began and to never forget those who fell first , '' said Rumsfeld , who despite his high office helped carry the wounded from the burning building seven years ago . `` We will never forget the way this huge building shook . We will not forget our colleagues and friends who were taken from us and their families . `` And we will not forget what that deadly attack has meant for our nation . '' Watch Rumsfeld speak » . Rumsfeld donated hundreds of thousands of dollars of his own money to help build the Pentagon memorial . President Bush followed Rumsfeld at the lectern . `` On a day when buildings fell , heroes rose , '' Bush said . `` ... One of the worst days in America 's history saw some of the bravest acts in America 's history . '' Watch Bush speak » . After the ceremony , participants moved through the memorial , finding and touching the benches honoring loved ones , colleagues and fellow citizens . Earlier , a bagpiper walked alone across the Pentagon memorial playing `` Amazing Grace . '' Watch the bagpiper 's moving solo » . Seven years ago , al Qaeda terrorists used hijacked airplanes to attack the World Trade Center and the Pentagon -- the twin symbols of America 's financial and military might . Another hijacked plane crashed in Pennsylvania . iReport.com : ' I just sat in my car and cried ' At the Pentagon , the ceremony dedicated a memorial to the 184 victims killed when American Airlines Flight 77 struck the building 's west wall . An American flag was raised smartly to the top of a flagpole , then slowly lowered to half-staff , and a band played the national anthem . Watch and listen to Thursday 's ceremonies » . At the White House , President Bush and first lady Laura Bush , along with Vice President Dick Cheney and his wife , Lynne , observed a moment of silence on the South Lawn at 8:46 a.m. , the moment when American Airlines Flight 11 struck the north tower of the World Trade Center . In New York , Mayor Michael Bloomberg introduced a moment of silence also at 8:46 a.m . Throughout the day 's ceremonies , he was also to call for moments of silence to mark the time the second plane hit the south tower , the fall of the south tower , and then the fall of the north tower . Watch an audio slide show about that day » . `` We come each year to stand alongside those who loved and lost the most , to bear witness to the day which began like any other and ended as none ever has , '' Bloomberg said . Flanked by police officers , firefighters and other officials , Bloomberg quoted what he called an Irish proverb : `` Death leaves a heartache no one can heal . Love leaves a memory no one can steal . '' Watch Bloomberg honor the victims » . Relatives then began to read the names of the 2,751 victims at the crash site , commonly called ground zero . Moments of silence were also observed at 9:03 a.m. , the moment in 2001 that the south tower of the World Trade Center was struck by United Airlines Flight 175 ; 9:59 a.m. , when that tower fell ; and 10:29 a.m. , marking the collapse of the north tower . The New York Stock Exchange observed a moment of silence before its opening bell sounded . In Shanksville , Pennsylvania , Sen. John McCain , the Republican presidential nominee , spoke for less than two minutes at a ceremony to remember the 40 passengers and crew of United Airlines Flight 93 , who perished after the hijacked plane went down in a field there . Watch Americans remember 9/11 victims » . It is believed that the passengers and crew , aware of the fate of at least some of the other hijacked planes , fought back against the men who had taken control of their aircraft , leading to its crash . The services were held at a temporary memorial near the western Pennsylvania crash site . McCain and his Democratic counterpart , Sen. Barack Obama , agreed to suspend campaigning for the day . Both candidates were to take part in a wreath-laying ceremony at the World Trade Center site at 3:30 p.m .
NEW : Former defense secretary donated thousands for memorial . 'On a day when buildings fell , heroes rose , ' president says . Day 'began like any other and ended as none ever has , ' New York mayor says . Watch 9/11 memorials in New York and Washington on CNN.com Live .