New Yorkers paused in silence at 8:46 a.m. on Wednesday to mark the moment the first plane struck the World Trade Center in the September 11, 2001 attacks twelve years ago.
"It brings back the hard memories, but this is where I need to be on this day," said Brian Branco, 47, who attended the ceremony.
Branco, who has the names of his three friends tattooed on his arm, escaped the 78th floor of the South Tower. Of the five who worked together only two made it out alive.
The remembrance was the first to be held after the April bombing of the Boston marathon, considered the first act of terrorism successfully carried out on U.S. soil since the attacks of 2001.
"It was just horrible to remember that it can happen again at anytime and anywhere," said Deborah Burton, 53. She came to the commemoration in honor of her friend, Joyce Ann Carpeneto who died in the North Tower.
Relatives gathered in the plaza of the 9-11 Memorial to read aloud the names of the 2,983 who died in the 2001 attacks on the World Trade Center and the Pentagon and the foiled hijacking of Flight 93, as well as those who perished in the 1993 World Trade Center Bombing.
Wednesday's ceremony was one of many that occurred around the country to mark the twelfth anniversary of the September 11 attacks.
President Barack Obama and Vice President Joe Biden observed a moment of silence on the White House lawn for the victims of the attacks.
In Boston, where the two planes that were crashed into the Twin Towers took off, a commemoration gathering at the Massachusetts capitol building included a separate moment of silence for those who died in the April bombing.
"A lot of people fail to acknowledge that two of the planes took off from Boston," said Christie Coombs in an interview with Kyodo News before the day of the memorial. Coombs' husband, Jeff, was aboard the plane that crashed into the North Tower.
Coombs was also near the finish line of the Boston Marathon on April 15, 2013 when two pressure cooker bombs went off killing three people and injuring over 200 others.
"The really scary thing about that day, April 15, is that it reminded us again of how vulnerable we are," said Coombs.
For Coombs and other relatives of 9/11 victims, the bombing reawakened the shock and pain they felt after the attacks in 2001. But soon after, those in Boston were asking how to help the victims of the bombing.
Beth Chambers, a Boston social worker who has worked with the relatives of 9/11 victims for twelve years told Kyodo News that their experience can help the bombing victims' families.
Having attended the trial of Zacarias Moussaoui, a French citizen who was convicted of conspiracy in the New York attacks, some who lost loved ones on 9/11 will meet with family members of Boston bombing victims to help prepare them for the trial of Dzhokhar Tsarnaev, one of the alleged bombers, Chambers said.
The non-profit Coombs established in her husband's memory is also assisting some of the Boston bombing victims.
Helping others after their own tragedies won't bring Coombs' husband back, she said. "But it makes us feel better. The fact that we are able to do things like that in Jeff's name, I know it would make him smile," said Coombs.