Danielle Booker hugs her mother, Sharon Booker, as the two remember Sean Booker, Danielle's father and Sharon's husband, at the National September 11 Memorial & Museum during a ceremony on Saturday in Manhattan. Sean Booker was a technician on the 93rd floor of the World Trade Center's north tower when he was killed during the 2001 attacks.

Danielle Booker hugs her mother, Sharon Booker, as the two remember Sean Booker, Danielle's father and Sharon's husband, at the National September 11 Memorial & Museum during a ceremony on Saturday in Manhattan. Sean Booker was a technician on the 93rd floor of the World Trade Center's north tower when he was killed during the 2001 attacks. / Denver Post via Getty Images

Updated September 11, 2021 at 3:34 PM ET

On the 20th anniversary of the Sept. 11 attacks, multiple ceremonies commemorated the nearly 3,000 lives that were lost on that day.

From New York to Pennsylvania to the Pentagon, here are some of the scenes captured as people are remembering and reflecting on the lives lost and legacies left behind.

New York City

In New York City, those honoring those killed gathered Saturday morning in Lower Manhattan at the National Sept. 11 Memorial & Museum. The museum is located on the spot where the twin towers fell.

A family member grieves at the National 9/11 Memorial and Museum ceremony commemorating the 20th anniversary of the 9/11 attacks on the World Trade Center, in New York City on Saturday.

A family member grieves at the National 9/11 Memorial and Museum ceremony commemorating the 20th anniversary of the 9/11 attacks on the World Trade Center, in New York City on Saturday. / AFP via Getty Images

Family and friends carry photos of some of the more than 2,600 victims to the ceremony commemorating the 20th anniversary of the 9/11 attacks on the World Trade Center.

Family and friends carry photos of some of the more than 2,600 victims to the ceremony commemorating the 20th anniversary of the 9/11 attacks on the World Trade Center. / Getty Images

Family members and loved ones of victims attend Saturday's ceremony in New York City. Six moments of silence were held, marking when each of the World Trade Center towers was struck and fell, and the times corresponding to the attack on the Pentagon and the crash of Flight 93.

Family members and loved ones of victims attend Saturday's ceremony in New York City. Six moments of silence were held, marking when each of the World Trade Center towers was struck and fell, and the times corresponding to the attack on the Pentagon and the crash of Flight 93. / Getty Images

Former President Barack Obama (from left), former first lady Michelle Obama, President Biden, first lady Jill Biden and former New York City Mayor Michael Bloomberg attend 9/11 commemoration ceremony in New York City.

Former President Barack Obama (from left), former first lady Michelle Obama, President Biden, first lady Jill Biden and former New York City Mayor Michael Bloomberg attend 9/11 commemoration ceremony in New York City. / AFP/Getty Images

Bruce Springsteen performs

Bruce Springsteen performs "I'll See You In My Dreams" during an unannounced appearance at the Sept. 11 anniversary ceremony in New York City. / AP

Arlington, Va.

In Arlington, Va., a ceremony was held at the National 9/11 Pentagon Memorial honoring the 184 people killed when American Airlines Flight 77 crashed into the west side of the Pentagon.

An attendee reacts during a 9/11 remembrance ceremony at the Pentagon in Arlington, Va., on Saturday.

An attendee reacts during a 9/11 remembrance ceremony at the Pentagon in Arlington, Va., on Saturday. / AFP via Getty Images

U.S. service members attend the 9/11 observance ceremony at the National 9/11 Pentagon Memorial in Arlington, Va.

U.S. service members attend the 9/11 observance ceremony at the National 9/11 Pentagon Memorial in Arlington, Va. / Getty Images

Defense Secretary Lloyd Austin (left) and Chairman of the Joint Chiefs of Staff Gen. Mark Milley stand for the national anthem during the Pentagon 9/11 observance ceremony.

Defense Secretary Lloyd Austin (left) and Chairman of the Joint Chiefs of Staff Gen. Mark Milley stand for the national anthem during the Pentagon 9/11 observance ceremony. / Getty Images

Shanksville, Pa.

Attendees gathered at the Flight 93 National Memorial in Shanksville, Pa., in a ceremony attended by Vice President Harris, second gentleman Doug Emhoff, and former President George W. Bush.

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Charlie Greene places flowers for his father Donald Greene, who perished on Flight 93, during a ceremony Friday at Flight 93's Memorial Plaza in Shanksville, Pa.

Charlie Greene places flowers for his father Donald Greene, who perished on Flight 93, during a ceremony Friday at Flight 93's Memorial Plaza in Shanksville, Pa. / Bloomberg/Getty Images

People listen as Vice President Harris speaks on Saturday at the 20th anniversary remembrance of the Sept. 11 terrorist attacks at the Flight 93 National Memorial in Shanksville.

People listen as Vice President Harris speaks on Saturday at the 20th anniversary remembrance of the Sept. 11 terrorist attacks at the Flight 93 National Memorial in Shanksville. / Getty Images

An attendee puts her hand on the head of a child at the Flight 93 National Memorial in Shanksville.

An attendee puts her hand on the head of a child at the Flight 93 National Memorial in Shanksville. / Anadolu Agency/Getty Images

Bells are rung during a 9/11 commemoration at the Flight 93 National Memorial in Shanksville.

Bells are rung during a 9/11 commemoration at the Flight 93 National Memorial in Shanksville. / AFP/Getty Images

Visitors line the Wall of Names at the Flight 93 National Monument during the Luminaria Ceremony on Friday in Shanksville. The ceremony honors the 40 victims of Flight 93.

Visitors line the Wall of Names at the Flight 93 National Monument during the Luminaria Ceremony on Friday in Shanksville. The ceremony honors the 40 victims of Flight 93. / Getty Images

Tags: September 11, 2021  Ceremony  9/11 Memorial  September 11  9/11  Series: The 20th Anniversary Of The 9/11 Attacks 

Correction

Because of incorrect information from Getty Images, a caption on a previous version of this story misspelled Charlie Greene's last name as Green.