Americans remember 9/11 attack, first-responders' bravery in memorial ceremonies across US

Americans across the country are marking the 23rd anniversary Wednesday of the Sept. 11, 2001, terror attack on the U.S. with memorial ceremonies in Lower Manhattan, Pennsylvania at the Pentagon and elsewhere.

Nearly 3,000 people were killed on 9/11 when three hijacked planes struck their targets and a fourth was downed by crew and passengers near Shanksville, Pennsylvania.

The most deadly attack on U.S. soil and the bravery of first-responders are being marked with ceremonies at the World Trade Center in Lower Manhattan, where two planes individually struck the center's twin towers, toppling them and killing hundreds. The third struck the Pentagon, in suburban Virginia, just across the Potomac River from the nation's capital. 

Fresh off their debate Tuesday night, Vice President Kamala Harris and former President Donald Trump, the respective Democratic and Republican presidential nominees, attended the 9/11 observance at the World Trade Center and are scheduled to go to the Flight 93 National Memorial in Shanksville, according to the Associated Press.

President Joe Biden joined Harris at the New York ceremony and is scheduled to go with her to Pennsylvania and the Pentagon, where third commercial jets crashed after al-Qaida operatives hijacked them.

The attacks killed 2,977 people.