PHOTOS: America pauses to remember 9/11 victims

United States President Barack Obama and his wife Michelle along with former President George Bush and his wife Laura led the world in mourning the loss of nearly 3,000 people, who lost their lives exactly 10 years ago in the most fearful terror attack that changed the way we live.

Dressed in black, the two couples held hands as they walked slowly along the memorial, watching the wall etched with names of the 2,983 people killed in the terror unleashed by Al Qaeda chief Osama bin Laden.

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Even though bin Laden was taken out in unilateral raid by American military commandos on May 2 in Pakistan, the wounds of the victim's families, including Indians, remained fresh.

An eerie silence gripped the ground-zero as the America's first family along with Bush spent about a minute at the 30-foot waterfalls that are part of the new memorial.

People silently held on to American flags as well as photos of their loved ones who died when hijacked twin planes rammed into the iconic World Trade Centre in New York, bringing the skyscrapers down like a pack of cards.

The ceremony began with a procession of bagpipers and singing of the national anthem by a choir.

Tears rolled down the cheeks of many present as names of the victims were read out at the event, which was under heavy security cover, following fresh security alerts regarding a possible Al Qaeda attack.

Mayor Michael R Bloomberg said that the attacks had turned "a perfect blue-sky morning" into "the blackest of nights."

He added, "We can never unsee what happened here."

Former US President George W Bush was also present during the ceremony.

Bush read from the letter Abraham Lincoln sent to the mother who lost five sons in the American Civil War.

Later today, Obama will visit Shanksville, Pennsylvania, and the Pentagon near Washington, D.C.

The 9/11 attacks were a series of four coordinated suicide attacks in New York City and Washington, D.C. on September 11, 2001 in which 3,000 people were killed.