Most journalists could not get close to the scene. They were relying on rescue workers, rather than officials, to relay information. Many of those workers had been on the site for hours.

Then officials began to repeat parts of the same story.

On Thursday morning, a navy officer, Adm. José Luis Vergara, told Televisa that there appeared to be a girl inside but that they could not pinpoint her location. “There’s a girl alive in there, we’re pretty sure of that, but we still don’t know how to get to her,” Admiral Vergara said.

Then the navy backtracked. The Naval Secretariat said in a statement that 11 children had been rescued from the school, and that the bodies of 19 children and six adults had been recovered. But no students were believed to still be trapped inside, it said. The body of a seventh adult was discovered on Sunday.

“We want to emphasize that we have no knowledge about the report that emerged with the name of a girl,” the navy’s assistant secretary, Ángel Enrique Sarmiento, said last Thursday. “We never had any knowledge about that report, and we do not believe — we are sure — it was not a reality.”

Mr. Sarmiento said that a thermal camera lowered into the rubble of the school had detected blood, but that the only person still listed as missing was a school employee. At least one body was removed from the rubble last Thursday morning, after the Frida Sofia story emerged — that of a 58-year-old woman — and it could have been her fingers that rescuers had seen.