NEW YORK (REUTERS) – Scant hope remains of finding anyone alive in the ruins of the World Trade Center, a week after a terror attack collapsed the twin towers, authorities said Tuesday, moving closer to delivering the dreaded news that more than 5,000 missing people are dead.

Rescue workers digging at the site of the buildings, which were reduced to rubble by coordinated attacks from two hijacked planes, found nothing but bodies and body parts.

“The chances of recovering any live human beings are very, very small,” said Mayor Rudolph Giuliani. “We don’t have any substantial amount of hope that we can offer to anyone that we are going to be able to find anyone alive.”

The list of the missing stood at 5,422 people, he said. Only 218 were confirmed dead, 66 of them unidentified.

The dead hailed from 62 nations, U.N. Secretary-General Kofi Annan said.

“This is why no one can remain indifferent,” he said, urging world leaders to do as he did and see the devastation firsthand.

“To see it closer gives you a completely different dimension,” Annan said.

“They all know that we need to come together to defeat terrorism, and we have to cooperate across the board to be able to do it.”

Many people in the city paused with heavy hearts and teary faces to mark the exact moment at 8:48 a.m. (12:48 GMT), exactly one week after the first of two passenger airlines sliced into one of the two 110-story towers that symbolized America’s financial might.

A second plane rammed the second tower 18 minutes later, and the two tallest buildings in New York City later collapsed in terrifying clouds of smoke and flames.

Nearby buildings fell, burst into flames or nearly disappeared under a shower of concrete and jagged metal shards. Block after block was layered with dust and ash, and thousands fled.

Even as New Yorkers struggled to get back on their feet, returning for a second day to reopened financial markets, just a casual glance at the downtown skyline was a reminder that the two towers that many used to get their bearings from miles away simply were not there.

“I have a lot of moments where I simply can’t accept it,” said Giuliani, voicing the thoughts of countless others.

“I just keep thinking, ‘How could they have done this?’ When I woke up this morning a week later, there’s a certain part of you that says this actually didn’t really happen.”

Blocks from the disaster scene, New York Police Department Lt. Richard DiBlasio said he glanced over to “see what’s there, and what was there is not there anymore.”

“As each day goes by, it makes it more somber,” he said.

Yet despite fading hopes, when asked why the bucket brigades used to haul debris were no longer visible, Giuliani said: “We think they’re getting closer to the area where they could have some remaining hope that they could find a few people, and they want to be careful.

“They were on the exterior before, and now they’re moving into the interior,” he said.

Fire Commissioner Thomas Von Essen dampened hopes that someone could have survived in an air pocket.

“We are finding in some areas where there might be a void, the level of heat is so much that no one would have been able to survive,” he said.

More than 300 of the missing were firefighters and emergency services workers. They had rushed into the buildings to rescue people after the two planes struck and were buried in the collapses.

Workers were using heavy equipment to tear away at the mountains of pulverized concrete, remnants of building facades and twisted metal skeletons known as “the pile.”

Solemn caravans of trucks drove grim loads of debris to Staten Island’s Fresh Kills dump to be sifted through by criminal investigators looking for evidence in the devastating attacks.

In a second day of trading since the New York Stock Exchange reopened after a four-day closure, the Dow Jones Industrial Average dropped 17.30 points, or 0.19 percent, to 8,903.40. The blue-chip index had fallen sharply on Monday but never fell victim to the panicky selling some had feared.