MEXICO CITY -- Mexico City residents worked through the night into the early hours of the morning Wednesday, digging through immense piles of pancaked rubble that had once been high rise buildings searching for survivors of a devastating earthquake that killed more than 200 people across central Mexico -- more than half in the capital.
They worked in the dark and often with their bare hands, with power out across 40 percent of this city of 20 million and rescue and medical services stretched to their limit.
Volunteers, medics and marines worked side by side to clear away the chunks of concrete in the dusty air. Everywhere in the city, they formed lines to pass along containers filled with rubble and dump them into waiting trucks.
Cries of "silence" punctuated the work as people listened in hope for the sounds of survivors under the wreckage. At least 44 buildings collapsed or partly collapsed in Mexico City alone, according to Mayor Miguel Ángel Mancera.
The 7.1-magnitude earthquake struck 76 miles southeast of the earthquake-prone capital at 1:14 p.m., according to the U.S. Geological Survey and came on the 32nd anniversary of the infamous 1985 quake that killed thousands.
The head of Mexico's civil protection agency, Luis Felipe Puente, put the toll at 217, revising it down from earlier estimates.
Even as residents were trapped inside buildings across the city and in the surrounding towns, attention was riveted on a collapsed school in the southern neighborhood of Villacoapa, where rescuers pulled out 25 bodies from the wreckage -- all but four of them children, according to the federal Education Department. More are believed to be under the wreckage.
Rescue worker Pedro Serrano described to The Associated Press how he tunneled into the unstable rubble to a partially collapsed classroom of the school, only to find no one alive.
"We saw some chairs and wooden tables. The next thing we saw was a leg, and then we started to move rubble and we found a girl and two adults -- a woman and a man," he said.
Late on Tuesday night, President Enrique Peña Nieto urged calm in a video message, saying the "the priority at this moment is to keep rescuing people who are still trapped and to give medical attention to the injured people." He said 40 percent of the capital and 60 percent of the neighboring Morelos state, was without power.
The president had been traveling to the southern state of Oaxaca to inspect damage from an earlier earthquake when the latest one occurred, sending him back to the capital to convene a national emergency council.
Two weeks an even larger quake took place off the Pacific coast and shook the south of the country, killing nearly 100 people. Scientists said the same large-scale tectonic mechanism caused both events: The larger North American Plate is forcing the edge of the Cocos Plate to sink. This collision generated both quakes. But it was unlikely that the quake earlier this month caused Tuesday's disaster.
Mexico is particularly vulnerable to earthquakes: The country is in a region where a number of tectonic plates butt up against one another, with huge amounts of energy waiting to be unleashed.
Mexico City is partially built on old lake sediment, which is much softer than rock. The seismic waves can be amplified traveling through the sediment, Blakeman said, making the damage worse than in areas on more-solid ground. He said aftershocks were possible, too. The rupture was approximately 50 kilometers, or 31 miles deep, and as a rule, the shallower an earthquake is, the higher the chance for aftershocks. "Fifty kilometers is pretty shallow, so I would expect aftershocks," Don Blakeman, a geophysicist with the USGS said.
The USGS's model for estimating earthquake damage predicts 100 to 1,000 fatalities and economic losses of between $100 million and $1 billion for a temblor of this scale and proximity to population centers.
The quake shook Mexico City so hard that the murky, stagnant waters of the city's ancient Xochimilco canals were churned up, turning the waterways into rollicking wave pools. Videos posted to social media showed tourists in flat-bottomed tour boats struggling to stay in their seats and hold on to their beers.
In the central neighborhood of Del Valle, a frantic scene played out Tuesday afternoon as hundreds of people gathered to search for trapped residents. At least two multistory apartment buildings fell, and residents said dozens of people could have been inside.
At the Clínica Gabriel Mancera in Mexico City, more than a dozen hospital beds had been set up on the patio outside as a triage center on Tuesday afternoon. Leticia Gonzalez, a 45-year-old maid in a nearby apartment building, said she tried to race out of the building but concrete crashed down as she fled. Her right leg was wrapped in a bandage as she grimaced in pain outside the hospital.
"We were all running like crazy," she said. "This was the worst earthquake I've ever seen."
Marisela Avila Gomez, 58, was in her apartment in the capital's central Narvarte neighborhood when the shaking began, toppling her furniture and shattering the windows. A piece of glass sliced deep into her right leg.
"My whole house is full of blood," she said.
In a Twitter message Tuesday after receiving news of the quake, President Trump wrote: "God bless the people of Mexico City. We are with you and will be there for you."
In the capital's southern neighborhood of Coyoacan, the walls of colonial-era buildings cracked and sagged in the quake, with some collapsing into rubble. Residents hugged and cried in the streets. At the Barricas Don Tiburcio shop, shelves bearing food crashed down and wine bottles shattered on the floors.
"This is the worst one I have ever felt," shopkeeper Beatriz Aguilar Bustamante said. "I don't know if I will have a house when I go home."