NEW YORK (AP) – Americans are commemorating the Sept. 11 terror attacks with somber tributes, volunteer projects and a new monument to victims. Thousands of victims’ relatives, survivors, rescuers and others are expected at Tuesday’s ceremony at the World Trade Center.

President Trump and first lady Melania plan to join an observance at the 9/11 memorial near Shanksville, Pennsylvania, where there is a new tower honoring victims. Vice President Mike Pence is attending a ceremony at the Pentagon.

In all, nearly 3,000 people were killed on 9/11 at New York’s World Trade Center, the Pentagon and the Pennsylvania field. Medical Advances in DNA testing is helping to identify WTC victims to this day, 17 years later.