Rescue workers from around the world kept digging Thursday for possible survivors of this week's central Mexican earthquake as authorities said the number of deaths had risen to 273.
Confusion continued to surround the fate of a 12-year-old girl widely reported to have been discovered in the rubble of a school in southern Mexico City.
The Mexican navy, which is overseeing the search, said Thursday that all pupils at Colegio Enrique Rébsamen had been accounted for, leading to anguished reports that the girl had died or even that she never existed in the first place.
But "there are important indications of presence of life in the area of the incident," the navy said in a statement, which didn't address whether children who weren't enrolled in the school may have been at the scene.
Eleven children have been rescued from the school, which is named for Enrique Conrado Rébsamen Egloff, a 19th-century school reformer whose principles are still prominent in the country's education system. Tuesday's 7.1-magnitude earthquake killed 19 children and six adults, including a woman whose body was pulled from the wreckage on Thursday morning.
A sense of urgency permeated the scene as more than 700 rescue workers — some from as far away as Taiwan and Israel — continued digging after two days without sleep. Authorities told NBC News they were working on the assumption that survivors would be able to last only about four days.
Fatima Navarro, a teacher at the school, told Telemundo, NBC's Spanish-language network, that "we thought it was a heavy truck" when the ground began to tremble shortly after 1:40 p.m. Tuesday.
"When we realized it was not, we started to evacuate the children," Navarro said. "All of us who are alive feel so powerless that we couldn't help those who died."
An elite disaster team organized by the U.S. Agency for International Development — including 60 Los Angeles County firefighters and five search dogs — arrived in Mexico City on a C-17 transport from Travis Air Force Base, California. U.S. authorities the plane was delivering 62,000 pounds of equipment and medical supplies.
The office of President Enrique Peña Nieto revised the nationwide death toll to 273 late Thursday afternoon: 137 in Mexico City, 73 in Morelos, 43 in Puebla, 13 in the State of Mexico, six in Guerrero and one in Oaxaca.
"Let there be no doubt: The search-and-rescue work in collapsed buildings continues," said Peña Nieto, who visited hard-hit areas of Puebla, near the epicenter, on Thursday. "We are not going to suspend until the last of the survivors has been found."
In a heartening sign of progress, meanwhile, the Federal Electricity Commission said Thursday night that electricity had been restored to 95 percent of customers who were affected.
The Mexican soccer league, Liga MX, announced that all matches set for this weekend had been postponed until October. "We're inviting all our fans to participate and help at different collection centers in support of those affected by the earthquake September 19," the league said in a statement.
Two of the national team's biggest stars, Javier Hernández, the striker known as Chicharito who plays for West Ham United in the England Premier League, and Miguel Layún, a defender for Porto in the Portuguese league, set up a fundraising effort called #YoXMéxico to coordinate contributions to relief efforts.
The actress Salma Hayek launched a similar campaign on Crowdrise to support UNICEF relief efforts and donated the first $100,000 herself.