Vice President Kamala Harris attended the commemoration in lower Manhatten, along with NYC Mayor Eric Adams, Gov. Kathy Hochul, Senate Majority Leader Chuck Schumer, and other local and state leaders.

President Joe Biden was set to deliver remarks to service members, first responders, and their families in Alaska as he made his way back from the G20 in India.

The solemn gathering in the Financial District of Lower Manhattan has been held every year since hijackers crashed two jetliners into the World Trade Center, and another into the side of the Pentagon, while a fourth plane crashed in a Pennsylvania field after passengers staged a mutiny.

The nation was devastated as nearly 3,000 people were killed in the worst-ever terrorist attack on U.S. soil.

The memorial service where the iconic towers once stood includes a reading of victims’ names by surviving family members, and six moments of silence to mark the exact times when the two passenger jets slammed into the World Trade Center, when both towers collapsed, when a plane struck the Pentagon, and when Flight 93 crashed.

“It’s more important than ever that we never forget all those we lost and how New York stood strong in the aftermath of the Sept. 11 attacks,” said Matthew Ketschke, the president for Con Edison utilities of New York, which has rallied state funding to provide power to the memorial since 2002. “For 200 years, Con Edison has been a constant through our city’s brightest days and its darkest moments. Each year, the Tribute in Light is an iconic symbol of that strength, resilience, and New York’s forward progress.”

In a statement from the White House last week, President Biden proclaimed Sept. 8-10 as “National Days of Prayer and Remembrance,” — urging Americans to mark the anniversary with contemplative observances such as memorial services, the ringing of church bells and candlelight vigils.

Monday’s memorial service also comes days after New York City’s Chief Medical Examiner Jason Graham announced that DNA helped to identify the remains of two 9/11 victims who were nameless for more than two decades, while 1,104 victims remain unidentified, according to mayor Adams.

A number of separate 9/11 vigils and tributes, including a 5K run and walk, were planned in the coming days across New York’s five boroughs.

At dusk Monday, twin beams of blue light rising four miles from Ground Zero will light up the Manhattan skyline until dawn Tuesday.

At 11:30 a.m., the New York City Fire Museum will hold a wreath-laying ceremony at the museum to honor the 343 city firefighters who died while racing into the burning buildings to save lives.

Hochul has ordered flags to be flown at half-staff at all state government buildings, while 16 state landmarks, including the Empire State Building and Penn Station, will be lit in blue to honor the dead.

Elsewhere, New York Lt. Gov. Antonio Delgado will attend a 2 p.m. interfaith remembrance service at St. Peter’s Church, where the New York Port Authority will honor 84 employees who died in the attacks, as well as those who died in the 1993 terror bombing at the World Trade Center.

Staten Island residents will gather to honor the dead at the “Postcards” memorial site on the North Shore Waterfront Esplanade, where 274 plaques are displayed with the names, birthdays, job titles and profile silhouettes of those lost from the borough.

A day earlier, survivors and relatives of victims who were sickened or died from 9/11-related illnesses, including first responders and rescue and recovery workers, were honored at the site as part of an annual Community Day.

The former World Trade Center site, memorialized in 2002, includes a monument of black marble inscribed with the names of thousands who died, as well as two large, square reflecting pools, in the footprints of the original twin towers.