Breaking news update, posted at 1:18 p.m. PT
All children have been accounted for in a Mexican elementary school that was the target of search and rescue efforts, Mexico's sub-secretary of Navy said Thursday.
Angel Enrique Sarmiento said that there are possible indications that one person may still be alive inside Colegio Enrique Rebsamen.
"We have done an official count along with the directors of the school, and we are certain that all the children either passed away, are in local hospitals, or are safe and sound in their houses."
Original story, last updated 12:16 p.m. PT
Rescuers in Mexico City pushed through debris Thursday at an elementary school in an urgent attempt to reach a 12-year-girl, two days after a powerful earthquake trapped her and killed at least 250 people across central Mexico.
The rescue attempt at the capital's Colegio Enrique Rebsamen came amid concerns the structure could buckle further. It was one of many searches underway at buildings that collapsed in the region after Tuesday's magnitude 7.1 quake, the country's second major temblor in less than two weeks.
At the school, officials say 26 bodies -- including those of 21 children -- have been found and 11 people have been rescued. But a search for survivors intensified Wednesday when rescuers made contact with the 12-year-old girl and temperature readings suggested two others might be alive inside, CNN affiliate Foro TV reported.
Rescuers have been hauling chunks of lumber and concrete from the debris as others tried to shore up parts of the collapsed structure with beams. Workers were close to pinpointing the girl's location Thursday morning, Mexican navy Adm. Jose Luis Vergara told Foro TV.
"At this moment we know that at least one girl is alive inside," Vergara said.
Crews are trying to reach the girl through two routes, he said. Soldiers, rescuers and medics worked relentlessly, including some who said they had been there for 36 hours before being relieved.
Intermittently Thursday, workers held up their fists -- a gesture for silence so they could listen for signs of life. New discoveries appeared to be minimal. As of early Thursday afternoon, no one had been rescued, and only one body -- that of a woman -- had been removed from the rubble.
Shortly after a cloud of dust flew up from the site early Thursday, rescuer Alberto Salinas made a public plea on Foro TV, asking for beams, pulleys and other materials to shore up the structure. The building's remains must be reinforced to prevent further collapse, Vergara said.
Details of the rescuers' communications with the girl weren't immediately available, and seemingly contradictory information emerged. Vergara said the girl's precise location wasn't known, but Foro TV earlier reported that rescue teams had given her oxygen and water.
Families of students who died there, meanwhile, were making funeral arrangements Thursday -- and sharing those plans with each other through a WhatsApp messaging group they had joined before the earthquake, said Marisol Alexander, a woman who lives near the school.
Two earthquakes in 12 days
Tuesday's quake turned dozens of buildings in central Mexico into dust and debris, killing at least 250 people, Mexico City Mayor Miguel Angel Mancera told Foro TV.
President Enrique Peña Nieto has declared a national emergency, and the country is observing three days of national mourning. Tuesday's quake came 12 days after a 8.1 magnitude earthquake hit farther south on September 8, killing nearly 100 people.
An unaccounted number of people are staying at shelters around Mexico City after losing their homes. Schools have closed indefinitely, and millions remain without power.
Mexico's President asked people to stay indoors and away from the streets while rescue attempts continue. Still, residents are joining forces with rescue workers to search for survivors.
In Mexico City's Condesa section, a large rescue operation was underway Thursday at a collapsed building that had housed an outsourcing company. Elsewhere in the neighborhood, police blocked a road leading to a food processing company that also was damaged.
Cristobal Perres Garcia, 59, said police told him that one of his cousins -- a worker at the food processing plant -- was among several who died when it collapsed.
In Puebla state, southeast of Mexico City, the quake crumbled a church, killing a girl who was being baptized and 11 others attending the event, Gov. Tony Gali said. More than 9,700 homes and 100-plus government buildings were damaged in the state, Gali said.
There were more than 100 deaths in Mexico City, one of North America's most populous metropolises with more than 21 million people. Other deaths included 69 in Morelos state, 43 in Puebla state, 13 in the state of Mexico, four in Guerrero state and one in Oaxaca state, according to Luis Felipe Puente, national coordinator of civil protection for the Interior Ministry.
To provide some scope of the affected area, Oaxaca de Juarez, the capital of Oaxaca state, is almost 480 kilometers (300 miles) from Mexico City.
Just hours before Tuesday's quake, authorities held a citywide drill on the anniversary of the 1985 earthquake that killed an estimated 9,500 people in and around Mexico City.
'I thought someone was kicking my chair'
About 2,000 public schools were damaged in Tuesday's quake, Secretary of Public Education Aurelio Nuños said. Sixteen of the 212 affected schools in Mexico City had serious damage, he said.
At the private Colegio Enrique Rabsamen, where rescuers are trying to reach the girl, the temblor caused the school to fold in on itself, sandwiching and collapsing classroom onto classroom.
Foro TV interviewed two girls who said they were doing their English homework as the building began to shake.
"I thought someone was kicking my chair, but I turned around and no one was kicking me," one girl told the station.
"The English teacher said there was a quake. Our teacher took us to the stairs, and that's when part of the building started to come down. There was dust everywhere. We couldn't see."
The loss of lives weighed heavily on volunteers at the school site such as Ivan Ramos, whose son survived.
"This is a tragedy," he said. "It's kids. It will take a long time to heal."