The quake, which struck on the anniversary of the 1985 Mexico City natural disaster that killed more than 10,000 people, came as the country was still recovering from a deadly magnitude-8.1 tremor on September 8 in its south.
A doctor working with rescuers on the scene identified the girl to the Associated Press as "Frida Sofia", and said he told rescuers that at least five other children were also trapped alive under a collapsed wing of Enrique Rebsamen School. It says all the children have been accounted for, adding that they have either passed away, are in local hospitals, or are safe at home. According to ABC News, 11 people have been rescued from the school and three are still missing.
Luis Hinojosa told CBS7 he got a message a relative that live near Mexico City, and he was shocked to learn what had just happened.
In Mexico City alone, more than 1,900 people have been treated in health facilities after the quake and majority have been discharged, according to Pena Nieto. Rescuers are racing against the clock to find them.
Frida Sofia (full name not disclosed) was believed to have been one of the deceased until heat sensors used by emergency crews picked up activity from under the ruins of the building Wednesday. People were trapped underneath collapsed buildings. She carries a camera on her harness to help rescue forces see areas that are otherwise inaccessible.
Authorities said rescue work was still being carried out in eight of the 38 collapsed buildings across the capital.
Rescue workers clear the rubble in search of survivors in Mexico city, on September 19, 2017. Rescuing such a vulnerable individual would have been a ray of hope for a country still trying to locate people in the rubble.
Mexico's army also has rescue dogs digging through the debris of damaged buildings, and a dog named Maya from the Jalisco state government was credited with finding two dead bodies on Thursday.
"I need to recognize the volunteers who are unconditionally helping those who need it", Pena Nieto said.