Ceremonies were held Friday in New York City, Virginia and Pennsylvania.
Friday marks 25 years since the Sept. 11, 2001, terror attacks, which claimed the lives of 2,977 people at the World Trade Center, the Pentagon and Shanksville, Pennsylvania.
Another 9,000 people have died from 9/11-related illnesses over the last 25 years.
Victims' families, first responders and politicians gathered for annual remembrance ceremonies at the memorials in downtown Manhattan, the Pentagon in Virginia, and Shanksville, as Americans across the country pause to remember and reflect.
"9/11 Tribute in Light: Live from Lower Manhattan," a one-hour ABC News multiplatform live special, premieres on Friday, Sept. 11, at 8:00 p.m. EDT across ABC, Disney+, Hulu, National Geographic, ABC Owned Television Stations livestreams and ABC News Live.
The reading of the names at the 9/11 Memorial & Museum ceremony was paused once again at 9:59 a.m., when the fourth bell tolled, marking the time the World Trade Center’s South Tower collapsed.
A moment of silence was held at the Pentagon at 9:37 a.m. when a plane struck the building.
The crowd listened intently as the names of all of those who were killed in the attack were read, and a bell was rung.
President Donald Trump and first lady Melania Trump have arrived at the Pentagon in Virginia. Trump is expected to deliver remarks during the ceremony.
The third bell tolled at 9:37 a.m., which is the time American Airlines Flight 77 crashed into the Pentagon.
