Thursday marked 24 years since the Sept. 11, 2001 terror attacks, when al Qaeda hijackers crashed four passenger jets into the World Trade Center, the Pentagon and a field in Shanksville, Pennsylvania. 

The attacks forever changed New York City and the world, and the heaviness of the loss has not dimmed over the years.

Every year, the city and nation pause to remember the 2,983 people killed in the 2001 attacks and in the 1993 World Trade Center bombing. A solemn ceremony, including six moments of silence, was held Thursday morning at the 9/11 Memorial & Museum in Lower Manhattan. 

It's a day of reflection and of remembrances steeped in sorrow, as family members vow to keep their loved ones' memories alive, fulfilling the sacred promise to never forget. 

New York City Mayor Eric Adams was among the mourners gathered at Ground Zero, along with New York Gov. Kathy Hochul, former Gov. George Pataki, New Jersey Gov. Phil Murphy, and former Mayors Rudy Giuliani and Michael Bloomberg. FBI Director Kash Patel and Deputy Director Dan Bongino could also be seen in the crowd. 

Hochul directed more than a dozen state landmarks, including One World Trade Center and the Empire State Building, to be illuminated with blue lights Thursday in observance.

"Today I join the world in remembering the nearly 3,000 souls taken on 9/11, the people who went to work and never came home, and the brave heroes -- uniformed and otherwise -- who ran toward danger to save others," the governor said in a statement.

"Many of our enemies, foreign and domestic, thought we were going to collapse as a country, but we got up 9/12," Adams said before the ceremony. "Teachers taught, builders built. We showed the globe our resiliency, even in the midst of pain."

Adams' mayoral opponents, former Gov. Andrew Cuomo and state Assemblyman Zohran Mamdani, were also in attendance, while Republican Curtis Sliwa was scheduled to visit a different 9/11 tribute in the Rockaways. 

Meanwhile, President Trump observed 9/11 at the Pentagon before heading to New York for the Yankees game Thursday night. Vice President JD Vance was expected to be in Manhattan, but he is instead traveled to Utah following the assassination of conservative activist Charlie Kirk, a source told CBS News.

Annual reading of names at 9/11 remembrance

Family members of those killed in the attacks read through all the victims' names. Decades later, many of the speakers were the grandchildren of those who died.

"Grandpa Eddie, even though I never knew you, I still feel your presence in my daily life -- from the times when I get the hiccups and my mom says you're visiting me, to the moments my mom gets a good parking spot and we say you're a good parking attendant in the sky," one young reader said. "Our family says that I have a lot of your traits, they say I'm kind and generous like you. And even though I didn't have the chance to meet you in person, I still have a deep love and affection for you. I hope to be just like you when I grow up." 

"I never got to meet my Aunt Brooke. When I was younger, I knew that Brooke only got 23 years of life, but to a 5-year-old, 23 doesn't sound so young. But now standing here today, as a 22-year-old who just graduated college, it weighs heavy on my heart, mind and spirit that 23 years old is a child, 23 is a young person finding their place in the world," said another reader.

"My grandfather, Edward Thomas Keane. Pop Pop, it feels like twice every day I catch the clock at 9:11, and I wish you were here to help me make sense of this world," one grandchild said.  

It's a day to think of all those special moments missed and the pain of what might have been.

"My husband, Bernard Pietronico, 24 years feels like 24 minutes. You have two beautiful grandchildren, and I know you are watching over them," said the wife of one victim.

"My husband, Edward Frank Pullis. This year is more difficult because two of our three children are getting married, and you can't walk your princess down the aisle. You are missed every day," the wife of another victim said.

There were the youngest mourners, who came carrying memories they've only heard.

"To my grandmother, Louise A. Lynch, who will forever be in our hearts, and every day, I ask my mom for another thing to learn about her," one child said.

"My uncle was taken from us on the day the world will never forget. I stand here honoring my grandma's wishes for the new generation to say his name. Dear Alex, we love you ... and our family misses you and Grandma always," another child said.

Family members say their loved ones may be gone, but their spirit is still alive.

"We can feel your presence in every sign that you send, from the dragonflies by the pool, the dimes on the sidewalk and every lyric of 'I Hope You Dance,'" one reader said.

While tears were shed, there was also the memory of a city that, in its worst hour, bounced back, built back, and most importantly, its people stood side by side with each other.

"On September 12h, this nation was united in unspeakable tragedy," one speaker said. "It didn't matter what ethnic origin, religion, political affiliation or socioeconomic status you were, we were all united in grief and love. Our better angels prevailed, and may they prevail again."

"We have to remember those that are suffering still, 24 years later"

They also thanked the heroic first responders, the number of people who have died of 9/11-related illnesses now surpasses the deaths on 9/11.

Tens of thousands more are sick.

"We gotta remember those who are sick and dying. We have to remember those that are suffering still, 24 years later," 9/11 first responder and advocate John Feal said.

Feal has been fighting in Washington, D.C., to expand funding for the World Trade Center Health Program. The program is funded through 2090, but Feal says with more people getting sick every year, it could run out of money for new patients in 2027.

He says outside of New York, "never forget" gets forgotten.

"Slowly, we're turning into Pearl Harbor," Feal said. "People need to be educated on this in elementary school, middle school, high school and college, so this country never forgets."

Timeline of 9/11 moments of silence

Special coverage began on CBS News New York at 8:25 a.m. 

The ceremony wrapped up more than four hours later, shortly after 12:30 p.m.

At exactly 8:46 a.m., the first citywide moment of silence was held to mark when Flight 11 struck the North Tower. 

• 7:30 a.m. - Families and guests gather at the 9/11 Memorial & Museum
• 8:25 a.m. - Special coverage of the 9/11 ceremony begins on CBS News New York
• 8:40 a.m. - Procession including the flag, pipers and drummers
• 8:44 a.m. - Singing of the Star Spangled Banner
• 8:46 a.m. - First moment of silence, marking the moment the the North Tower was struck by hijacked Flight 11
• 8:48 a.m. - Reading of the names begins
• 9:03 a.m. - Second moment of silence, marking the moment the South Tower was struck by hijacked Flight 175
• 9:37 a.m. - Third moment of silence, marking the moment the Pentagon was struck by hijacked Flight 77
• 9:59 a.m. - Fourth moment of silence, marking the moment the South Tower fell
• 10:03 a.m. - Fifth moment of silence, marking the moment hijacked Flight 93 crashed in Shanksville, Penn. 
• 10:28 a.m. - Sixth moment of silence, marking the moment the North Tower fell
• Approximately 12:15 p.m. - Taps will be performed at the conclusion of the reading of the names, concluding the ceremony
• 3:00 p.m. - 9/11 Memorial & Museum reopens to the public

Street closures for 9/11 ceremony

The 9/11 Memorial & Museum is located at the World Trade Center site in Lower Manhattan. The museum closed early Wednesday and is not open to guests Thursday, so victims' loved ones can visit privately.

Drivers should plan for the following street closures around the area:

• Areas bounded by Barclay Street on the North; Rector Street on the South; Broadway on the East; West Street on the West (All Inclusive)
• Liberty Street between West Street and South End Avenue
• Albany Street between West Street and South End Avenue
• West Thames Street between West Street and South End Avenue
• South End Avenue between Liberty Street and West Thames Street
• Battery Place between West Thames Street and 3rd Place
• 3rd Place between Battery Place and Little West Street
• Little West Street between 3rd Place and Battery Place

The memorial comes amid the United Nations General Assembly, which may bring additional closures to the East Side of Manhattan.