NEW YORK, Sept. 11 (Xinhua) -- Flags were flown at half-staff, wailing bagpipes reverberated through the streets, and a moment of solemn silence was observed across New York City on the anniversary of the 9/11 terrorist attacks that killed nearly 3,000 people here 18 years ago.

An annual remembrance ceremony was held on Wednesday morning at the Ground Zero National September 11 Memorial & Museum in Lower Manhattan, where the World Trade Center Twin Towers once stood.

It was a personal event for family members and friends of the victims, whose names were recited one by one in a solemn process which lasted several hours.

Representatives took turns to the podium to tell the stories of their lost loved ones, while many stood silently in tears while others held photos of the victims.

After the ceremony was over shortly after midday, several people stayed on at the Memorial pools in the blockaded area, looking for a quiet moment to express their grief.

The bronze panels skirting the edge of the pool of the memorial were shining under the sun, with lines of victims' names inscribed there evoking haunting memories of the attack.

A woman in black stared at the name of the person she's been missing for 18 years, carefully putting several white roses onto the panel while whispering a prayer.

Unable to hold back her tears, an elderly couple standing nearby handed her a napkin and tried to console her with an assuring pat on her shoulder.

A senior gentleman brought his grandson to "meet" someone the toddler had never seen before, just to make sure this dark chapter in history would never be forgotten for generations to come.

Petra Schmidt came here for her former colleagues at Aon, an insurance company which had offices in both of the Twin Towers.

"We lost 176 people," she said. "We do this every year. It's very important to us. We never want to forget what happened here, and we want to make sure our colleagues are remembered."

Walking out of the Ground Zero in the uniform of the New York City Fire Department (FDNY), Joseph Donavan is one of the first responders of the attacks.

When the tragedy happened, he had already retired as a firefighter for the New York Stock Exchange. However, he still rushed to the scene as the second plane pummeled into the south tower.

"The noise was inexplicable. I thought the building snapped in half, to tell you the truth," Donavan recalled.

He came here every year over the past 18 years to remember his 343 former colleagues of the FDNY killed that day, including his cousin Gerald Duffy, who worked at the Ladder Company 21, a firehouse that lost seven members.

"I'll be here until I can't come here (anymore). And I hope God gives me the strength to keep coming back for a while longer," said the 80-year-old.

Donavan worked at the site for 10 months in the aftermath of the attacks. Six years ago, he was diagnosed with lung cancer.

The number of rescuers, cleaners and civilians who have been diagnosed with various diseases after being exposed to toxics in the 9/11 debris, like Donavan, is increasing.

On July 23, U.S. Senate approved a bill that ensures financial support through 2090 for medical claims of thousands of first responders of 9/11.

"That was a fight, but it had to be done," Donavan commented on the passing of the bill. "I'm fine now. But there are thousands of people who caught a disease related to the 9/11."

Though it's always a tough day on Sept. 11, Donovan said "it's gotten better" and his cousin's family is "well supported and they are coming along fine."

"Everybody has to move on. You can't carry this thing forever. So you have to move on at some point in time," said the veteran fireman who worked 25 years rescuing people's lives.

Donavan's following destination was the FDNY Memorial Wall located across the street, where a wreath was laid at the center and many passers-by stopped to hold a moment of mourning.

"I can find my cousin's name on the wall. I'm going to give a salute and I go on my way," he said.