Transcript for Devastating earthquake in Mexico leads to race for survival
Reporter: Tonight, MARIA's direct hit devastating Puerto Rico. The first category 4 storm to strike Puerto Rico in 85 years, slamming ashore around sunrise. Roofs peeled from buildings. Debris flying. Many of these homes not built to withstand any hurricane, let alone a category 4. We're outside of San Juan in a town hit very hard. A lot of destruction to homes, downed trees and power lines. Now dealing with this, flooding in every direction. Up to 30 inches of rain in some areas engulfing whole neighborhoods. 12,000 people needing to get to shelters, including a hotel's ballroom. ??? terrified residents singing about strength during trying times, to ease the fear. ??? for "Nightline," I'm Victor Oquendo, San Juan, Puerto Rico. Our thanks to Victor. We turn to another developing story tonight. That powerful earthquake in Mexico. More than 200 people confirmed dead. Many others missing after dozens of buildings collapsed. Now rescue teams working around the clock to clear the rubble and free people trapped inside. ABC's Matt Gutman is in Mexico City tonight as people scramble to find survivors. Reporter: Here under tons of brick and concrete, a race against time. To save the life of a girl trapped inside the Enrique repsmen elementary school, the wing collapsing after that devastating 7.1 magnitude earthquake which struck Mexico on Tuesday. It was a three-story building. It pancaked into a one-story building. They think they hear something and they're trying to listen to see if they can hear a survivor in the rubble. Officials tell ABC news they believe there are at least two others trapped with her. At least 21 children or teachers were killed. At least 11 people from that school have been rescued. Like these children. They're terrified, dusty, but alive. Miraculously saved after being buried under the rubble. Workers are now racing to save that little girl and whomever else may be trapped with her. They don't know exactly where she is inside the building. Bucket brigades, people removing brick by brick from that collapsed school. Looks like they're going to send the dog in that tiny crevice between what was I guess the second and third story. Now they're lifting the dog to the roof. Again, hoping to catch a scent of whomever might be inside still. 13-year-old Rodrigo one of the lucky ones crawling out of his collapsed school. The others who were rescued were listed on these handwritten slipts of paper with their names and the hospital where they could be found. That 7.1 quake striking central Mexico on Tuesday, shortly after 1:00 P.M. Local time. I'm in Mexico City airport. The whole building started shaking. Reporter: Shaking lasted for several agonizing minutes. It got even more intense and really started shaking. People trying to grab the tables and walls. Reporter: Jesus lives with his wife and baby girl next to that elementary school. Were you here during the earthquake? Yep. It was really, really scary. Scared my baby. I grabbed my baby and I saw the school collapsed and I thought, we are next. Everything was moving so bad. I couldn't actually walk. The ground was shaking so much you couldn't walk? Exactly. When I heard the thunder of the school going down -- I just looked at the window and it was like this big huge smoke of dirt. Right, the dust. And we started hearing the screams, really loud, coming from the school. We just lost the building. Mexico City. Reporter: The quake so far claiming the lives of more than 200 people in Mexico, causing extensive damage to Mexico City. 100 miles from the epicenter. Everyone ran outside of our office. And crowded into the streets. Lots of people crying, hugging, calling friends and family. Reporter: It was powerful enough to level at least 44 buildings, including homes, schools, and offices. Things in your house are falling over and shattering. Reporter: Inside this newsroom, the walls shaking. Throughout central Mexico, those choking clouds of dust. People panicking and praying. We still don't know if there's aftershocks, we don't know if there's going to be a power line coming down. There's debris still falling from buildings. Reporter: Windows slipping down buildings like sheets of ice. Debris crushing vehicles. The water at this park splashing as if in a giant bathtub. Rescue workers scrambling to find the missing. Overnight they clawed at the wreckage, some with bare hands. Mexico is no stranger to earthquakes. Mexico City was built in an old lakebed. And so it has this layer of very soft soils. The soils there amplify shaking by a factor of 100 or more. By comparison the worst we get in L.A. Is about a factor of 5. Reporter: The U.S. Is gearing up to help. This disaster assistance response team from Los Angeles deploying to Mexico to help with the search and rescue. Stunningly -- the quake struck just hours after the country had conducted earthquake safety drills. Drills that were put into place after Mexico's deadliest earthquake in 1985, which killed thousands. That was 32 years ago to the day. Tuesday's earthquake is the second to strike Mexico in just the past two weeks. On September 7th, close to midnight, a massive 8.1 magnitude earthquake hit off the country's southern coast. Houses were toppled. The quake introduced tsunami waves that sent people running into the streets in panic. That earthquake claimed the lives of at least 90 people. In general, whenever you feel earthquakes you've got to expect to feel more. And about 5% of the time the triggered earthquake ends up being bigger than the first one. Reporter: Back here in Mexico City, in the midst of so much loss, there are so many signs of generosity. Jesus nungeri remembers rushing to the collapsed almost tear school, moving rubble with his bare hands, just him and other neighbors. You were there trying to pull away the rocks. You still heard people inside the rubble screaming? At the beginning, yes. Yes. And then did the screaming die down? Yes. Yes, sorry to say, died down. Stayed there until we pulled out kids. And I saw it. And they put his own sweater on his face. And they pulled him out on a -- Stretcher? Was he alive? No. Reporter: Hope is not yet lost for the others still missing. The calls for dogs and doctors intensifying as the rescues continue. We've been granted permission to get as close as you can get to the school. You can see where they're trying to peek through the cracks. The eerie sound of silence, despite that massive crowd. You see those hands in the air, they've called for silence. That means they're trying to listen to see if they can hear the person they're looking for inside. It's incredible, probably 1,000 people around here, but it's eerily quiet when they raise their hands. It is agonizing work. But after nearly 24 straight hours of desperate effort, rescuers finally make contact with the little girl they have reportedly given her water and oxygen. But now they have to find a way to reach her and the others. Still in a day and in a country that has been filled with grief, a glimmer of hope tonight. For "Nightline," I'm Matt Gutman in Mexico City.
This transcript has been automatically generated and may not be 100% accurate.