Rescue workers were continuing to dig through rubble as dawn broke in Mexico City, searching for dozens of children feared buried beneath a school among hundreds of buildings destroyed by the country's most lethal earthquake in decades.
The magnitude-7.1 quake on Tuesday (local time) killed at least 217 people, nearly half of them in the capital, 32 years to the day after a devastating 1985 quake.
Among the twisted concrete and steel ruin of the Enrique Rebsamen school, soldiers and firefighters found the bodies of at least 22 children and two adults, while another 30 children and 12 adults were missing, President Enrique Pena Nieto said.
Hundreds of emergency workers spent the night pulling rubble from the ruins of the grade school with their bare hands under the glare of floodlights.
Three survivors were found at around midnight as volunteer rescue teams known as "moles" crawled deep under the rubble.
On Wednesday morning, the workers said a teacher and two students had sent text messages from within the rubble — parents clung to hope that their children were alive.
"They keep pulling kids out, but we know nothing of my daughter," said 32-year-old Adriana D'Fargo, her eyes red, who had waiting for hours for news of her seven-year-old.
The earthquake toppled dozens of buildings, tore gas mains and sparked fires across the city and other towns in central Mexico — falling rubble and billboards crushed cars.
In a live broadcast, one newsreader had time to say "this is not a drill," before weaving his way out of the buckling studio.
Parts of colonial-era churches crumbled in the state of Puebla, where the US Geological Survey (USGS) put the quake's epicentre some 158 kilometres south-west of the capital, at a depth of 51 kilometres.
As the earth shook, Mexico's Popocatepetl volcano, visible from the capital on a clear day, had a small eruption. On its slopes, a church in Atzitzihuacan collapsed during mass, killing 15 people, Puebla Governor Jose Antonio Gali said.
In Rome, Pope Francis told pilgrims he was praying for the victims, the wounded, their families and the rescue workers in the majority Catholic country.
"In this moment of pain, I want to express my closeness and prayers to all the beloved Mexican people," he said.
US President Donald Trump said in a tweet: "God bless the people of Mexico City. We are with you and will be there for you."
The disaster came as Mexico was still reeling from a powerful tremor that killed nearly 100 people in the south of the country less than two weeks ago.
Residents of Mexico City, a metropolis of some 20 million people, slept in the streets while authorities and volunteers distributed food and water at tented collection centres.
Other volunteers, soldiers and firefighters formed human chains and dug with hammers and picks to find dust-covered survivors and dead bodies in the remains of apartment buildings, schools and a factory.
With power out in much of the city, the work was carried out with flashlights and generators. Rescue workers requested silence as they listened for signs of life.
Some volunteers in Mexico City expressed frustration at the disorganisation among military and civilian emergency services, which competed over who would lead the rescue efforts.
The quake killed 86 people in the capital by early Wednesday morning, according to Civil Protection chief Luis Felipe Puente, fewer than he had estimated earlier. In Morelos State, just to the south, 71 people died, with hundreds of homes destroyed. In Puebla at least 43 died.
Another 17 people were reported killed in the states of Mexico, Guerrero and Oaxaca. The governor of Morelos state declared five days of mourning.
As many as 4.6 million homes, businesses and other facilities lost electricity, according to the national power company, including 40 per cent of homes in Mexico City.