Rescue workers raced against time today as chances diminished of finding survivors among the ruins of hundreds of collapsed buildings here following the most serious earthquake in the country's history.

But while the death toll mounted in the Obrera and Doctores neighborhoods -- the most seriously affected by the quake -- the living took up the task of coping with life among the ruins with remarkable equanimity and resilience.

The front of the seven-story Anadel dress factory, on San Antonio Abad and Gutierrez Najera streets, had totally collapsed. The top three stories were flattened and the caved-in center dripped gobs of concrete and streams of window draperies.

On the sidewalk a row of soldiers stood at attention, making sure that bystanders did not approach.

One of the bystanders was Cristina Chavez Borja, and she was waiting for word about the approximately 200 fellow seamstresses who were probably trapped inside.

She had crawled out from the ruins of the building 48 hours earlier, miraculously unscathed down to her long, glossy, pink fingernails, but shock and fear still edged her voice and dilated her pupils.

"I was changing into my work clothes when it hit," she said. "There was no time to think, to do anything. I don't really know how we got out. I just crawled."

She said the factory's personnel director had counted 25 survivors among the list of 250 seamstresses who were due to report for work at 7 a.m. Thursday morning. On Friday, she said, she watched rescue workers bring out two injured survivors and two corpses.

Now she watched as dozens of volunteers scrabbled ineffectually on top of the ruins, searching for a way into the compressed top three stories of rubble where the seamstresses are believed to be.

"We know there were some alive yesterday because we heard the moans," she said.

The seamstresses are among the still uncounted thousands who may add to the death toll in the earthquake, and the anguish of waiting for confirmation was taking its toll on relatives.

One woman who had been to all the city's improvised morgues looking for her daughter, Eugenia Ardanza, arrived at the ruins of the dress factory, where she said Ardanza worked, almost incoherent with shock.

"I know she is still alive in there," she said, producing a photograph of a smiling, round-faced teen-ager. "Please tell your newspaper to help me get her out."

As surprising as the collapsed mountains of apartment buildings and factories in this working class neighborhood was the matter-of-fact way in which residents were coping with the disaster.

This city of 12 million residents, in a metropolitan area of more than 17 million, is often cited in planning and urban development congresses as the world's largest ongoing urban catastrophe. Coping with what is reported to be the world's most severe environmental pollution, worst traffic and overstrained public services has given its citizens a grim stolidity that stood them in good stead today.

At the huge Chapultepec subway station on the edge of the Zona Rosa tourist neighborhood, thousands headed for work this morning while women fanned coal braziers on the sidewalk to prepare the spicy finger foods Mexicans love to eat for breakfast.

Less than 20 blocks away, in the working class areas behind the Zona Rosa's expensive hotels, streams of people left cordoned-off buildings marked for demolition. Many were headed for improvised shelters set up by the government, but others were making use of Mexico's strong extended family network to find shelter.

"We're going to my cousin's in Toluca," said one woman. "Things will be better there. Our building isn't so damaged, but the ones around it are beginning to smell because of the bodies inside, and that isn't good for the children. My husband will be coming back to guard against looters."

Down the street from the Anadel dress factory, hundreds of people stood in line with brightly colored plastic buckets, waiting for a water tank truck. Although the neighborhood had been without electricity or water for more than 48 hours, no one seemed impatient.

Elsewhere, groups of neighbors were lifting buckets of dirty water out of underground mains. Men were helping each other lift bundles of clothing and precious possessions -- a television set, a record player -- out of devastated buildings.

One man emerged from the ruins and showed all that he had been able to salvage for his new life -- an umbrella and an embossed plastic wastebasket.