NEW YORK, Sept 11: Families, friends, dignitaries and onlookers gathered at the World Trade Center's site (Ground Zero) on Saturday to remeber nearly 3,000 people killed in terror attacks on WTC and other cities.

The official World Trade Center memorial ceremony which was televised the world over, opened with bagpipers and drummers playing solemn music.

People nationwide, observed Sept 11 in their own ways, with services at local firehouses, memorial dedications, bell-ringing events and flag-hoisting ceremonies.

At precisely 8:46am, the exact time the first plane struck the North Tower, New York Mayor Michael Bloomberg introduced the first of four moments of silence and then led pairs of parents and grandparents as they read aloud the 2,749 names of the victims.

In Washington, President George W. Bush also observed a moment of silence on the White House's south lawn.

While last year's anniversary ceremony focused on the children who lost their loved ones, this year the theme was centered upon the parents and grandparents of the deceased.

While the names were being read out, immediate family members and other relatives descended a ramp to the lowest level at Ground Zero where they could lay flowers, reflect and pray.

The second moment of silence were marked at 9:03am, coiinciding the attack of the second plane.

The program ended at noon. Some 150 Muslims including Pakistanis and Bangladeshis were killed in the Sept 11, 2001 attacks.

CLAIM: Three years after the attacks on the WTC, the agency that owned and operated the twin towers said on Friday that it would sue the Saudi Arabian government's claim of unspecified amount of damages on behalf of it's 84 employees who were killed in the attacks.

Officials at the Saudi embassy in Washington were not immediately available for comment.