The baby had no vital signs when she was born, hospital director Dr. Jose Luis Meirino told CNN.
The gynecologist on hand didn't find any signs of life, so he passed the baby to a neonatal doctor who also didn't find vital signs, Meirino said.
The doctors observed the baby for a while, and only then, pronounced her dead.
Two morgue workers then put her body inside a little wooden coffin and placed it in the morgue.
"Up to that point, there were still no vital signs," the hospital director said.
That night, mother Analia Boutet insisted on seeing her dead daughter's body, Veron said.
"They put the coffin on top of a stretcher and we looked for a little crowbar to open it because it was nailed shut," Veron told a local television station. "It was nailed shut. I put the crowbar in there and started prying. I took a breath and took the lid off."
Boutet approached the baby's body, touched her hand, and heard a cry, Veron told CNN.
Veron's brother-in-law rushed the baby back to the neonatal ward. He clutched her close to his chest for warmth. She felt like an ice-cold bottle against his body, the relative told Veron.
"I can't explain what happened. Only that God has performed a miracle," Veron said.