Young children pulled from rubble of collapsed Mexico City school

— -- Students of the Mexico City school that collapsed after a powerful earthquake hit Tuesday afternoon were seen being pulled out of the rubble in dramatic video posted to social media.

When first responders and bystanders notice an opening in the building's structure, they rush to it and begin pulling the facade from the exterior in an effort to enlarge the hole, the video shows.

Rubble from the building litters the streets as the rescuers crouch down to retrieve the survivors. First responders are seen attempting to reassure crying children as they are picked up, out of the destroyed building. Yelling from inside the building informs the search team that there are more survivors.

Search-and-rescue teams continued to frantically search for victims trapped under the rubble of the Enrique Rebsamen primary and secondary schools on Wednesday, more than 24 hours after the earthquake struck.

The bodies of 21 children and four adults have been discovered at the said, said Mexico's Education Minister Aurelio Nuno. Eleven people have been rescued and three are still missing.

Rodrigo Heredia, a 13-year-old student, told a Televisa reporter in Spanish that he escaped the building because of an earthquake drill held earlier in the day on Tuesday.

City-wide earthquake drills were held to commemorate the 32nd anniversary of the Michoacán earthquake of 1985, which killed thousands and caused catastrophic damage in Mexico City.

The 7.1 magnitude earthquake struck near the town of Raboso in Puebla state Tuesday afternoon, according to the United States Geological Survey. It marked the second powerful quake to hit Mexico in last than two weeks, after an 8.1 magnitude earthquake struck off the country's Pacific coast 12 days earlier.

ABC News' Fergal Gallagher, M.L. Nestel and Morgan Winsor contributed to this reported.