Mexico's President President Enrique Pena Nieto has declared three days of mourning for the victims of an 8.1-magnitude earthquake.
Countries across Latin America have been expressing solidarity as the death toll continues to rise.
61 people are now confirmed to have died and at least 200 others were injured.
The quake, which struck late on Thursday off the southern coast, was the strongest to hit the nation since 1932.
Pena Nieto has been visiting some of the worst affected areas in the states of Oaxaca and Chiapas.
The president said 45 deaths had been reported in Oaxaca, 12 in Chiapas and four in Tabasco.
The Oaxacan town of Juchitan bore the brunt of the disaster, with sections of the town hall, a hotel, a church, a bar and other buildings reduced to rubble.
"The situation is Juchitan is critical; this is the most terrible moment in its history," the local mayor, Gloria Sanchez.
The quake had more force than the devastating 1985 temblor which flattened swathes of Mexico City and killed thousands.
This time damage to the capital was limited as the quake was deeper and farther away, but it still sent thousands of people running from their homes onto the streets when the violent rumbling began that also shook Guatemala and El Salvador.
Ecuador's President Lenin Moreno tweeted that the people of Ecuador “woke up with a sentiment of solidarity” with their “Mexican brothers,” adding that his Mexican counterpart Enrique Pena Nieto could rely on his administration for support.
From Bolivia, President Evo Morales also expressed solidarity to the people of Mexico, both affected by the earthquake: “We are ready to collaborate,” he added from his twitter account.
The Venezuelan Foreign Ministry also issued a message of support to the peoples of Mexico and Guatemala — which is now experiencing aftershocks from the earthquake, promising to send “all the help that the victims need” and to collaborate in the reconstruction efforts.
Mexico is now preparing for Hurricane Katia, expected to make landfall in the south on Friday night, as a series of natural disasters hits the region.
The National Coordinator of Civil Protection in Mexico, Luis Felipe Puente, posted on Twitter that the center and north of the state of Veracruz and eastern Puebla are on a red alert due to the approach of Hurricane Katia.
Warnings have also been given for Tamaulipas.
Three people died on Thursday in landslides triggered by heavy rains as the storm made its initial approach.