( CNN ) -- A bell tolled , ground zero fell silent . At 8:46 a.m. , hundreds who gathered at the site of the fallen World Trade Center towers paused in silence to mark the moment when American Airlines Flight 11 crashed into the north tower -- the opening salvo of a terrorist attack that brought down the iconic buildings , killed 2,977 people and launched more than a decade of war . Bagpipers broke the silence , and family members of victims of the 1993 bombing of the World Trade Center and the 2001 attack began a solemn reading of the names of those killed at the site . The 9/11 attack killed 2,753 people in New York , including 403 police and firefighters . The 1993 bombing killed six people . In Washington , President Barack Obama , Vice President Joe Biden and their wives also paused in silence outside the White House to commemorate the 9/11 victims . The Justice Department also held a moment of silence , . Another moment of silence was held in New York at 9:03 a.m. , when the second jetliner , United Airlines Flight 175 , crashed into the World Trade Center 's south tower . And at the Pentagon , where American Airlines Flight 77 crashed at 9:37 a.m. on September 11 , Obama laid a wreath and then spoke at a private observance for family members of the 184 people who died there . `` Our hearts still ache for the futures snatched away , '' he said . In southwestern Pennsylvania , where United Flight 93 crashed into a field near Shanksville , a bell tolled after the name of each of the passengers and crew members was read . Members of the crew of the USS Somerset rang the bells . The Navy named the ship in honor of Flight 93 passengers who fought back against their hijackers . Forty passengers and crew died when the plane went down . On the steps of the capitol , members of Congress also gathered to mark the occasion . It was the same place where lawmakers gathered 12 years before in the aftermath of the attacks to demonstrate unity . `` This moment is to pray for the families of the departed , and to ask God to renew our strength and replenish our grace , so that we may press on and serve without growing weary , and walk without growing faint towards that more perfect union of our founders dreams , '' said House Speaker John Boehner . `` That is why we return to these steps today , that is why we will always return . And that is why we will never forget . ''
Then : ` ` We will never forget , '' House ##man Baker says . ` ` Our hearts still ache , '' President Bush says at the Pentagon . In New York , Washington and Pennsylvania , bells and moments of silence .