Juarez Hospital's 13-story central tower was filled nearly to capacity, recalled nurse Aurora Alvarez, when the earth rumbled without warning and the building fell in a heap.

"It was like a thunderclap," said Alvarez, who has worked at the low-cost public medical facility for 14 years. "You could hear people screaming in the background. But what I remember most is the noise of the tower coming down."

Rescue workers slowly picked through the rubble of the destroyed hospital building today as hundreds of friends and relatives of those thought to be trapped inside watched quietly. At least 650 patients and more than 100 hospital workers and medical students were in the tower when it fell, Alvarez and another hospital employe estimated.

By this afternoon, about 350 bodies had been extracted from the twisted ruins. Several dozen victims were pulled from the rubble alive.

Elsewhere in the city, hundreds of others waited as workers pried through the debris of buildings where survivors had been freed. In a secondary school about 30 blocks from Juarez Hospital, 200 students were reported to have been buried. Workers pulled one boy out alive, and as many as 30 were reported to be conscious by rescue officials who said they had heard muffled shouts.

In most buildings toppled when the earthquake hit Thursday morning, however, there were no survivors.

In the Tlatelolco public housing complex, one 14-story apartment building collapsed with 600 inhabitants inside, none of whom has been found alive.

At the Juarez Hospital, cranes and heavy earth-moving equipment stood idle next to the crumbled tower as government officials defended the apparent inaction to an impatient crowd.

"Please, senora, listen," pleaded a Social Security Institute doctor, gesturing at the wreckage. "There could be dozens of people still breathing in there, and if we started using bulldozers we could suffocate them."

"The man makes sense," agreed Melesio Escobar Flores, one of the many relatives of victims who had stayed and donned red volunteers' badges. His 69-year-old mother-in-law had traveled four hours to Juarez Hospital on Wednesday to see a doctor about a hernia.

"We have been helping out here since the first thing Thursday morning," Escobar Flores said.

"What we have been doing here since Thursday is waiting," said Emilio Escobar, gently correcting his uncle. "We have been waiting."

A.D. Horne of The Washington Post Foreign Service compiled the following from reports by The Associated Press, United Press International, Reuter, Agence France-Presse and Deutsche Presse-Agentur:

In the middle-class Roma residential district near the heart of Mexico City, a man was trying to move a pile of rubble with his bare hands. He was searching for the bodies of his wife and three sons, who were in their second-floor apartment when he left for work shortly after 7 Thursday morning.

"I was a few steps away from home when everything started to move," he told an Agence France-Presse reporter. "I knew what was going to happen. It was unbelievable. I was rooted to the spot, watching the building collapse with my wife and children dying inside."

Across the city, there were similar scenes. In Tlatelolco, a district of large office and apartment buildings, the 30-story Nuevo Leon apartment complex collapsed. The newspaper Excelsior estimated that at least 1,000 persons were trapped in the rubble.

Jorge Herrera had just left the building for work when the ground began to move. "It just came down like a pack of cards," he said. His wife and two sons were inside and feared lost.

At the intersection of the city's two major arteries, Insurgentes Avenue and Paseo de la Reforma, the top three floors of the popular Continental Hotel crumbled, dropping blocks of masonry through the roofs of two school buses parked nearby.

Across the same busy intersection, an eight-story insurance company building collapsed. Around the corner, in an office building on the Reforma, correspondent David Cemlyn-Jones had just opened the 10th-floor bureau of Reuter news agency when he felt the floor shaking.

"I ran for the stairs and stumbled down the full 10 stories, with chunks of masonry falling around me and blocking my path," Cemlyn-Jones said. "I made it to the street, but not by much."

Wherever buildings collapsed, rescue workers searched through the rubble, listening for faint cries that would guide them to trapped survivors.

"We know there are people in there, we know," a soldier said outside a badly damaged apartment building. "But it's just too weak, and it's too dusty and smoky and we just can't go in there."

At one collapsed apartment building, rescue workers and volunteers formed a human chain of about 50 persons to pass injured survivors, some of them on stretchers, from the ruins to the street.

Outside the rubble of one apartment house, Juventino Benito Hernandez and his wife sobbed for their 2-year-old daughter and two sons, aged 8 and 3. The couple had left for work before the quake struck, Hernandez said, and he had rushed back to find the building destroyed.

"I called for my children," Hernandez said. "But there was no answer."