With solemn tributes, the United States is marking the 10th anniversary of the September 11 terrorist attacks that killed nearly 3,000 people and launched the country into a decade of war.
Events were held at the sites of each attack a decade ago — New York, the Pentagon outside Washington, and in Shanksville, Pennsylvania.
In New York City, a moment of silence marked when the first plane struck at 8:46 a.m., and silence fell again at 9:03 a.m. in observance of when the second hijacked jetliner struck the South Tower. Attendees also paused to remember when each of the towers fell.
At the Pentagon, a silent tribute was held at 9:37 a.m. local time, to remember the 184 victims of the crash of Flight 77 into the massive Defense Department headquarters.
President Barack Obama and his predecessor George W. Bush on Sunday morning toured the recently finished memorial at the site of the World Trade Center in New York.
After the first moment of silence, President Obama read a Bible passage that speaks of God as refuge and strength. After the second moment of silence, former president Bush read a letter of support from then-president Abraham Lincoln to a mother who had lost all five of her sons in America's Civil War.
At the Pentagon, Vice President Joe Biden spoke of the bravery of first responders and those who joined the military after September 11, 2001. Defense Secretary Leon Panetta said the events of September 11 have since strengthened and inspired the country.
In New York, those who lost family and loved ones in the attacks read the names of the nearly 3,000 victims of the terrorist attacks.
After New York, the Obamas will travel on to Pennsylvania, to remember the victims of Flight 93. Later, they will attend a wreath-laying ceremony at the Pentagon.
On Sunday evening, Mr. and Mrs. Obama will attend “A Concert for Hope” in Washington .