Over 1,000 victims remain unidentified 22 years after 9/11 attacks

People attend a commemoration ceremony of the 22nd anniversary of the 9/11 attacks in New York, the United States, on Sept. 11, 2023. The commemoration ceremony was held here on Monday to mark the 22nd anniversary of the 9/11 attacks. (Photo by Michael Nagle/Xinhua)

NEW YORK, Sept. 11 (Xinhua) -- Over 1,000 victims remain unidentified as the United States on Monday marked the 22nd anniversary of 9/11 attacks.

A commemoration ceremony was held on Monday at the National September 11 Memorial &Museum in Lower Manhattan, New York, where the 2,977 people killed in the Sept. 11, 2001 attacks were honored.

Days ahead of the anniversary, the identification of two victims - a man and a woman whose names are withheld at the request of their families - from the deadliest terror attack on U.S. soil was announced.

The two new identifications represented the 1,648th and 1,649th persons identified since 2001 using advanced testing by New York City's DNA Laboratory, according to a press release by the mayor's office on Friday.

They were the first new identifications of World Trade Center victims since September 2021. However, 1,104 victims - 40 percent of those who died - remained unidentified, it said.

The number of 9/11 first responders who have died from Ground Zero-related health complications is nearly equal to the number of first responders who died during the attacks.

"When the towers fell on that terrible day, we lost 343 New York City Firefighters. ... In the years that have followed, over 341 more FDNY members have died from rare cancers and diseases caused by the toxic dust at Ground Zero," the Uniformed Firefighters Association of Greater New York wrote in a Facebook post on Monday.

People attend a commemoration ceremony of the 22nd anniversary of the 9/11 attacks in New York, the United States, on Sept. 11, 2023. The commemoration ceremony was held here on Monday to mark the 22nd anniversary of the 9/11 attacks. (Photo by Michael Nagle/Xinhua)

Flowers and flags are seen placed on plates inscribed with names of 9/11 victims at the National September 11 Memorial and Museum in New York, the United States, on Sept. 11, 2023. The commemoration ceremony was held here on Monday to mark the 22nd anniversary of the 9/11 attacks. (Photo by Michael Nagle/Xinhua)

Firefighters mourn for victims at the National September 11 Memorial and Museum in New York, the United States, on Sept. 11, 2023. The commemoration ceremony was held here on Monday to mark the 22nd anniversary of the 9/11 attacks. (Photo by Michael Nagle/Xinhua)

Flowers and flags are seen placed on plates inscribed with names of 9/11 victims at the National September 11 Memorial and Museum in New York, the United States, on Sept. 11, 2023. The commemoration ceremony was held here on Monday to mark the 22nd anniversary of the 9/11 attacks. (Photo by Michael Nagle/Xinhua)

People embrace during a commemoration ceremony of the 22nd anniversary of the 9/11 attacks in New York, the United States, on Sept. 11, 2023. The commemoration ceremony was held here on Monday to mark the 22nd anniversary of the 9/11 attacks. (Photo by Michael Nagle/Xinhua)

Family members read names of 9/11 victims during a commemoration ceremony of the 22nd anniversary of the 9/11 attacks in New York, the United States, on Sept. 11, 2023. The commemoration ceremony was held here on Monday to mark the 22nd anniversary of the 9/11 attacks. (Photo by Michael Nagle/Xinhua)

A man kneels in front of a plate inscribed with names of 9/11 victims at the National September 11 Memorial and Museum in New York, the United States, on Sept. 11, 2023. The commemoration ceremony was held here on Monday to mark the 22nd anniversary of the 9/11 attacks. (Photo by Michael Nagle/Xinhua)