NEW YORK -- New York City will never forget September 11, 2001.
Nearly 3,000 people were killed the day when hijackers used two passenger planes as weapons to topple the twin towers of the World Trade Center and another to attack the Pentagon.
A fourth hijacked plane went down in flames when heroic passengers fought back to bring it down in rural Pennsylvania before it could strike another high-profile target, probably in Washington.
Related: In memory of Don DiFranco, WABC engineer killed on 9/11
Looking at images from that day may be difficult for some.
Smoke, flames, and debris engulf the twin towers, as people on the ground, some covered in ash, watch in horror.
Photos: The aftermath of 9/11
Familiar landmarks, like subway stations, are completely destroyed, and one image shows the iconic city skyline covered in smoke.
View the photo gallery above to see images from that fateful day, and join us in remembering all those killed and those still suffering today.
Each year, New York City and millions around the country commemorate 9/11 with mournful ceremonies, volunteering, appeals to "never forget," and drawing attention to the terror attacks' continued toll on first responders.
Relatives of the victims descend on ground zero in Lower Manhattan, and the events of that terrible day and the weeks, months and years that followed are never forgotten, nor are the memories of those killed by terrorists in hijacked planes.
Related: Eyewitness News day-of-air coverage from September 11th, 2001
September 11 still shapes American policy, politics and everyday experiences in places from airports to office buildings, even if it's less of a constant presence in the public consciousness after 19 years.
The 9/11 commemorations are by now familiar rituals, but each year at ground zero, victims' relatives infuse the ceremony with personal messages of remembrance, inspiration and concern.
CLICK HERE for more Eyewitness News reflections, photos and stories marking the anniversary of 9/11
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PHOTOS: 9/11 attacks on the World Trade Center in New York City
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AP Photo/ CHAO SOI CHEONG