A firefighter pauses before the start of ceremonies at the National September 11 Memorial on Sept. 11, 2019, in New York City.

An American flag is left at the engraved names of 9/11 victims at the edge of the north reflecting pool during ceremonies commemorating the 18th anniversary of Sept. 11, 2001.

Firefighters and police rehearse before the start of ceremonies at the National September 11 Memorial.

A flag hangs on the Pentagon before a ceremony in observance of the 18th anniversary of September 11th.

A member of the US Army Old Guard stands on the grounds of the National 9/11 Pentagon Memorial.

Family members of the nearly 3,000 victims of 9/11 once again gathered Wednesday at the Ground Zero memorial site to mark the 18th anniversary of the Sept. 11, 2001, terror attacks.

Roughly 4,000 people, including throngs of uniformed members of the NYPD, FDNY and Port Authority, turned out for the somber annual ceremony to honor those killed in the deadliest act of terrorism on US soil.

The ceremony at the 9/11 Memorial plaza remembers the 2,983 men, women and children killed in the attacks on the World Trade Center, the Pentagon and aboard Flight 93 with the reading of the victims’ names. The reading also includes the names of the six people killed in the 1993 WTC bombing.

Ahead of the commemoration, the sounds of bagpipes were heard as mourners — some clutching photos of loved ones, others holding flowers or balloons — walked solemnly around the plaza’s twin reflecting pools that bear the names of the victims on bronze parapets.

Margie Miller lost her husband Joel Miller, who was an assistant vice president for firm Marsh and McLennan and was working on the 97th floor of Tower One when hijacked American Airlines Flight 11 crashed through floors 93 through 99.

“I come all the time, so I certainly come every anniversary,” said Margie, 69, of Baldwin, Long Island. “In many, many ways, this is our cemetery.”

She added, “He loved his work, he loved being here and to me, this is his place and it’s my place. It’s where I feel him. I feel this is the place I need to be to be closest to him.”

High schooler Kassidy Rieder, the daughter of retired NYPD cop and 9/11 first responder Nancy Collins, sang “The Star-Spangled Banner” at the start of the ceremony.

Collins worked on the rescue and recovery efforts at Ground Zero in the aftermath of the attacks until she found out she was pregnant with Kassidy.

As in years past, six moments of silence were observed – twice to mark the times that each hijacked plane struck the North Tower and South Tower (8:46 a.m. and 9:03 a.m.), twice to mark the times when each tower fell (9:59 a.m. and 10:28 a.m.), and to mark the moments of the attack on the Pentagon (9:37 a.m.) and the crash of the hijacked United Airlines Flight 93 near Shanksville, Pa. (10:03 a.m.).

Relatives, including young children, of the victims delivered emotional and sometimes tearful messages to their loved ones as they read off the names of the dead.

Sally Ryan choked back tears while talking about her “beloved” son Kevin James Murphy.

“You would be so proud of your now-grown children,” Ryan said. “I picture you often up in heaven together with your father, looking down on your family with pride and joy.”

Little Alexis Barbara remembered her grandfather, FDNY Assistant Chief Gerard A. Barbara.

“He had two children and a wonderful life,” Alexis said. “If he was still alive, I would not only think of him as my grandfather, but my role model … I love him with all my heart … I’ll never forget him.”

La-Shawn Clark, who lost her husband of 15 years, Benjamin Keefe Clark, in the 9/11 attacks, told the crowds of mourners that she’s soon expecting her first grandchild.

“There’s so many milestones that he missed,” an emotional Clark said. “This one is kind of hard.”

Benjamin, an executive chef for Fiduciary Trust in Tower Two, “got hundreds of people out” before he was killed, La-Shawn told reporters.

“He got all the staff out of the building,” said La-Shawn, who has five children with Benjamin.

Benjamin raced back in the building and tried to carry a quadriplegic woman down the stairs of the tower, she explained.

“They didn’t make it out,” La-Shawn said.

Speaking of the Ground Zero site, La-Shawn said, “I feel my connection here. This was the last place that he was.”

“This year hurt a little more because the grandbaby is on the way,” she said, later telling reporters that the due date is Oct. 7. “I know when I look at my children, I know he would be very proud of them.”

Thirteen-year-old Joey Henry, of Long Beach, read aloud names, including the uncle he was named after, FDNY firefighter Joseph Henry.

“It felt good to mean something special today and represent my uncle today,” Joey said afterward, noting how he enjoys listening to stories his uncle and how “he always wanted to be a firefighter.”

Joey’s dad and the brother of Joseph Henry, retired FDNY Lt. Edward Henry, who worked at Ground Zero in the aftermath of the attacks, said his brother’s remains were never recovered.

“They never found anything for him, so we really have no place else to go,” said Edward, who referred to his brother as a “good kid” who had been living with him before he was killed.

“He loved life, played basketball. Just loving everything – and then this happened,” Edward said.

Ruth Aron Green also read off names of the slain, including her son, Joshua Todd Aron.

“Josh, there are no words to tell you how much you are missed, how much we remember and miss you,” she said. “Every day is less valuable without you.”

Some relatives paid tribute to those who died of 9/11-related illnesses since the attacks.

Meanwhile, President Trump spoke at the Pentagon at an observance ceremony after he and First Lady Melania Trump observed a moment of silence on the South Lawn of the White House.

“For every American who lived through that day, the September 11th attack is seared into our soul. It was a day filled with shock, horror, sorrow and righteous fury,” Trump told the solemn gathering at the Pentagon.

Vice President Mike Pence delivered remarks at the annual remembrance ceremony at the Flight 93 National Memorial.

He said the memory of those killed in the Flight 93 crash is “carved into the hearts and memories of the American people.”