NEW YORK (AP) — Though weeks will pass, searchers will keep looking for survivors in the wreckage of the World Trade Center, New York's mayor said Thursday. But he conceded that some victims may never be found.

"That's a very strong possibility, that given the nature of this implosion and the temperatures — 1,000, 2,000 degrees Fahrenheit — that we will not be able to recover every single person," Mayor Rudolph Giuliani said on NBC's "Today" show.

Still, he said, "It'll never, ever be a situation in which we're not sensitive to and looking to see if there are people that are alive there.

"Even weeks ahead, while we're removing stuff, obviously we're going to be looking. Right now, the possibility still remains. They're slim, but they still remain."

As he spoke, a shaky semblance of day-to-day life returned to the city. Students whose schools were near the World Trade Center returned to class — but to different buildings, blocks away, where they'll share space and teachers.

Julie Hiraga's second-grade class at Public School 89, five blocks from the Trade Center, was moved to PS 3 in Greenwich Village. Teachers and students, she said, are trying to recover together from the trauma of the Trade Center attack.

"We all evacuated the building so teachers certainly are feeling their own sense of being scared and anxious," she said.

She said teachers had worked with therapists and counselors "to try and address those issues for ourselves so we could provide a safe environment for the children."

One of Hiraga's students, 7-year-old Melissa Watt, returned to school with a smile because "I know that everything's OK" — her family is safe. On the day of the attack she had worried because her mother, Monica, sometimes ran errands at the Trade Center.

The Watts live in Battery Park City, next to the Trade Center site, and have not been able to go home since hijacked planes topped the twin towers. They have been staying with Monica Watt's parents in New Jersey.

"We thought it was important to be here so she could see her friends," Monica Watt said.

In another sign of a city slowly coming back to life, two lanes of the Brooklyn Bridge between Brooklyn and Manhattan reopened Thursday morning. The bridge has been closed to motor vehicles since the attacks.

The first major New York sports event since the attacks came Wednesday night at Madison Square Garden, where the Rangers beat the New Jersey Devils in an exhibition hockey game. The crowd was announced at 14,646, but about half that many were in the stands.

On Friday, the New York Mets come home to Shea Stadium and a pennant race. But fans will face heightened security, including a ban on standing near the field to watch batting practice.

Meanwhile, rescue workers, pushed beyond human limits and losing hope of finding survivors, kept working. No survivors have been found since the day after the attacks.

"We're trying our best to keep morale up. We're all a little frustrated that we haven't been able to find anyone," said officer Bob Schnelle of the New York Police Department's K-9 unit. "But we're going to keep at it until they tell us to stop."

The bodies of 233 people have been recovered from the ruins. Of those, 170 have been identified by the coroner, and their families notified. Another 5,422 were missing.

The mayor said Yankee Stadium, in the Bronx, would be the site of a memorial service at 3 p.m. Sunday for fallen rescue workers. Admission will be by ticket only, and there should be room for about 60,000 mourners in a city of 8 million.

The tickets will be issued by organizations affiliated with police and fire departments. Details were still being ironed out.

Originally planned for Central Park, with an expected audience of a million, the service was relocated because of security concerns.

State officials said they were close to an agreement that would expedite issuing death certificates so families of the dead could more quickly obtain insurance and other benefits.

On Wednesday, Giuliani led French President Jacques Chirac on a tour of the command center set up after the attacks.

"When you see it from the air, there's an anger and determination to do something about it that I can't describe," Giuliani said.

Chirac praised firefighters, the mayor and residents for exhibiting calm and resolve. He also glimpsed his country's 1886 gift to America, the Statue of Liberty. It is still visible, but through smoke drifting from the still-smoldering rubble.

British Prime Minister Tony Blair planned to visit the city Thursday. And on Friday, the city was to receive a gift from Japan: $10 million in relief aid, according to City Council President Peter Vallone.

A new statue was on view in Manhattan — a bronze work that depicts a praying firefighter, down on one knee. It originally was cast to honor fallen firefighters in Missouri, but its maker and the foundation that commissioned it decided to donate it to New York.

Many stopped Wednesday to gaze at the statue, perched temporarily on a flatbed truck. Some lighted a candle or placed flowers around the base as others, visibly moved, bowed their heads.

"It touches you," said Hakeem Adesanya of Teaneck, N.J. "It makes you reflect."