NEW YORK — Cranes and bulldozers picked away the heaviest pieces of what's left of the World Trade Center, but the real work was unfolding on a smaller scale: rescuers with plastic pails, toiling in the muck and stink.

Exhausted but determined, hundreds of volunteers Saturday slogged their way through tons of rubble that became a mammoth mud pile after heavy rain the previous day. Plummeting temperatures before dawn sent workers rummaging through Salvation Army clothes for sweaters.

"I think the cold is great," said Kevin Kossi, a mechanical engineer who volunteered for the rescue effort. "You're working real hard and you're hot, so the cold energizes you."

By Saturday morning, 152 bodies had been recovered, with 92 identified. The number of people missing jumped by more than 200 to 4,972, said Police Commissioner Bernard Kerik.

One rescuer found the body of a flight attendant, her hands bound, The New York Times reported Saturday. Another worker told the paper he had found the remains of people strapped to what seemed to be airplane seats.

Among the missing are 23 New York police officers and hundreds of firefighters. Among the dead found so far were 18 city firefighters, three Port Authority police officers, two emergency medical technicians and a New Jersey firefighter.

A few blocks east of the disaster site, initial steps were taken to return at least part of lower Manhattan to normal. For the first time since the attacks, pedestrians were allowed into an area south of Canal Street that includes many financial businesses scheduled to reopen Monday.

Authorities on Friday announced the first arrest in the investigation of the attacks — a man held in New York as a material witness, meaning he was thought to have information relevant to the investigation.

Government officials said he was associated with the brother of Osama bin Laden, the Saudi exile who is the prime suspect in Tuesday's attacks, The New York Times reported.

The man later appeared in federal court in White Plains, but officials declined to identify him or say what information they were seeking. Court records were sealed.

On Friday, President Bush came to the trade center site, a fire helmet on his head and his arm around a rescue worker. "Thank you for your hard work," he said through a megaphone, vowing to "answer these attacks." The devastated downtown site echoed with chants of "USA! USA!"

The nation rallied to show its support in New York and beyond, with midday services to mourn the dead and, come evening, candlelight vigils flickering on street corners and at state capitols.

But as the hours wore on at the site where the 110-story World Trade Center towers stood, it became disturbingly clear: finding the victims was going to take a long time. And much of it was going to be done by hand.

Human chains — firefighters, police, National Guardsmen, construction workers and doctors — passed empty buckets into holes in the pile of rubble.

Somewhere inside, helped by search dogs and flashlights, were rescuers looking for bodies and survivors. The pails re-emerged, each containing a few chunks of debris. So far, more than 20,000 tons have been removed, a tiny fraction of the skyscrapers' ruins — a combined total of 220 stories of gleaming steel weighing some 1.25 million tons, plus an unknown number of surrounding structures.

Working 12-hour shifts, and sometimes double that, rescuers found things turning worse in Friday's downpour.

"You're cold, you're hands are numb, the steel is slippery," said Jesus Agosto, 40, a construction worker who volunteered from New Jersey.

Jerry Shike, who also works in the construction industry, volunteered from Connecticut. The muck, he said, was "just making things very difficult."

Weather aside, workers said they were driven by hope, no matter how often that hope was dashed.

"I was saying to myself, 'Give us some sound. Give us some sound,"' said volunteer Fred Medins. But each time someone thought they heard a faint cry for help, he said, it would turn to nothing.

City officials have turned away hundreds of volunteers, saying they have as many as space will allow. Still, some wait for hours at the rescue workers' staging area, hoping for a chance to help.

Access points to the area immediately surrounding the trade center complex were manned by the National Guard and New York police. Tents had been erected, and supply areas for food, clothing and equipment had been organized.

The rash of bomb threats in the city — averaging around 100 a day, compared with seven on the day before the bombings — brought an arrest Friday of a man who allegedly told police there was a bomb in a junior high school, Kerik said.

Kerik said several people had been arrested for using phony identification or pretending to be volunteers, then committing crimes in the cordoned-off disaster zone. And Mayor Rudolph Giuliani said a phony telemarketer was soliciting contributions for a nonexistent fund to help the families of victims.

"We'd really like to catch them and make an example of them," the mayor said.