New York ? An empty, flag-draped stretcher symbolizing all the victims of the World Trade Center attack who could not be found was carried from the rubble Thursday in a solemn, wordless ceremony marking the end of the agonizing, 8 1/2-month cleanup.

As victims’ families wept, the stretcher was carried slowly and silently past an honor guard of grieving relatives, police officers and firefighters, up a 500-foot ramp and out of the giant crater that used to be the basement of the twin towers.

Firefighters' helmets sit on a concrete ledge overlooking ground zero at the World Trade Center site in New York. A ceremony Thursday marked the symbolic end of recovery and cleanup efforts at the site of the terrorist attacks.

Then buglers played taps, police helicopters flew in formation overhead, and bagpipers performed a mournful march, then “America the Beautiful.”

Cathy Stefano, who lost her firefighter nephew Thomas Schoales, 27, said her family wept throughout the service.

“I was so taken by the absolute silence of thousands of people surrounding 16 acres, and nobody spoke,” she said.

The half-hour ceremony began with the bright ping of a Fire Department bell ringing 20 times in sets of five the 5-5-5-5 signal that dates to the 19th century and has come to symbolize the death of a firefighter.

The first set of bells echoed through the warm morning at 10:29 a.m., the exact time the second tower collapsed on Sept. 11 in a roar of twisting steel and falling concrete.

A stretcher bearing a folded American flag symbolizing all those who perished on Sept. 11 is carried up the ramp out of ground zero in New York. The ceremony Thursday marked the end of the cleanup effort at the World Trade Center site.

Christina Evans-Serafin, whose son was among the 343 firefighters killed, said that although some of her son’s remains have been identified, she was hoping recovery workers would find more of his body.

“You feel like you left something behind,” she said.

Of the 2,823 people killed in the attack, just 1,102 have been identified. Nearly 20,000 body parts have been recovered.

David Bauer III, a 17-year-old member of the honor guard, said that participating in the ceremony was like being a pallbearer for his father, a Cantor Fitzgerald employee whose remains have not been identified.

“This is the first time I’ve been here, and this is a nice way to say goodbye,” Bauer said.

During the procession, silence fell over the crowd of several thousand. Family members held photographs of their loved ones pressed over their hearts. Some wiped away tears. “We will never forget,” a banner read.

The stretcher was loaded into a Fire Department ambulance as rescue workers saluted. Police officers wept.

Paulina Cardona grieves at the end of the procession from ground zero, marking the official closure of recovery efforts at the World Trade Center site in New York. Cardona's husband, Jose, was among those lost in the attacks.

A truck carrying the trade center’s last steel beam, which stood until it was cut down Tuesday night, followed the stretcher. Draped in a black cloth and American flag, it was driven to a Kennedy Airport hangar to be put in storage, perhaps to be used someday for a monument.

At times, the only sounds were the rumble of vehicles and the breeze, which carried a trace of the acrid smell that hung over lower Manhattan for months after the attack.

Among those in the crowd were Mayor Michael Bloomberg and his predecessor, Rudolph Giuliani, who won acclaim for his stewardship of the city after the attack.

At the end, the crowd burst into applause for the officers, firefighters and construction workers leaving ground zero. Some tossed flowers into the void where the towers once stood. Many hung back after it was over, leaning over guardrails to stare into the crater.

“It was tough to come here every day, and now it’s tough to leave,” said John Keating, a Brooklyn firefighter.

The final pieces of rubble are expected to be removed by the middle of next week.

The cleanup was completed more than three months earlier than expected for less than $750 million, a fraction of the projected cost. Workers moved 1.8 million tons of debris in more than 100,000 truckloads during the round-the-clock operation.

Police Commissioner Raymond Kelly said about 800 officers who put in long hours at ground zero will undergo counseling beginning next week.

“This is a trauma never before experienced by a municipal police department,” he said. Port Authority and city fire officials have also offered counseling,

In Washington, President Bush thanked the workers who cleaned up the site and added that the country must “continue to offer our prayer to those families and friends and citizens who still hurt.”

The search for body parts will go on for months at a Staten Island landfill where the rubble has been taken. A development agency is already working on a plan for the rebuilding and the creation of a memorial.

Several family groups had asked Bloomberg to schedule the service on a weekend so that work and school would not be disrupted. The mayor said the city avoided the weekend so it would not conflict with religious observances. He also said May 30 was the traditional date for Memorial Day.

To accommodate those who could not attend the ceremony, the family groups have planned their own service at ground zero on Sunday.