Thursday marks the 24th anniversary of the 9/11 attacks on the United States, when nearly 3,000 people were killed when hijacked jetliners crashed into the World Trade Center, the Pentagon and a field in Pennsylvania on September 11, 2001.
A solemn ceremony will take place on Thursday at the 9/11 Memorial & Museum in Lower Manhattan, where the Twin Towers of the World Trade Center once stood.
The bell of hope is scheduled to ring out at St. Paul's chapel in New York as well to mark the moment at 08:46 a.m. local time (1246 GMT) when the first of two planes hit the Twin Towers on September 11, 2001.
Pentagon staff in Washington, D.C. attended an observance ceremony one day before 9/11 on Wednesday (September 10).
Osama bin Laden and al-Qaeda claimed responsibility for the suicide attacks 24 years ago, which led to a U.S.-led war in Afghanistan.
(Production: Soren Larson, Roselle Chen, Gabriel Goh)