The epicenter was near Crucecita, in the southeastern state of Oaxaca, with shock waves felt as far away as Mexico City, some 700 kilometers (430 miles) distant, where it sent frightened residents rushing into the streets.
The US Geological Survey reported that the quake struck with a magnitude of 7.4, at a depth of 23 kilometers. After initially publishing a reading of 7.1, the Mexican Seismological Service revised its figure to 7.5.
"It's confirmed it was a 7.5 magnitude. Fortunately there's no damage, in any case we're going to continue to call for caution as there may be aftershocks and we must all take care without worrying," said President Andres Manuel Lopez Obrador in a video published on social media.
"Strategic installations didn't suffer any damage, that is to say, ports, airports, refineries, hydroelectric plants, everything is in a good condition," said Lopez Obrador after speaking to David Leon, the national coordinator of Mexico's Civil Protection force.
Oaxaca Governor Alejandro Murat told Milenio TV station that "there was a small collapse, one person was injured and another died," adding that the state suffered minor damage.
Mexican Oil said its refinery in Salina Cruz, Oaxaca had been shut down as a precaution after a fire broke out "that was immediately stifled."
One person was injured while other refineries in the state are operating as normal.
The US Pacific Tsunami warning center initially said hazardous waves as high as three meters could strike anywhere within 1,000 kilometers of the quake's epicenter, affecting the Pacific coast of Mexico and Central and South America.
However, a few hours later it said the threat had "largely passed."
Quake adding to virus woes
Mexico City mayor Claudia Sheinbaum also activated response protocols, although she said there had been "no major incidents" reported.
The earthquake was felt in several parts of the capital of 8.8 million people which in 2017 was hit by a 7.1 magnitude quake that left 360 people dead throughout the country.
That same year, 96 people died after an 8.1 magnitude quake struck the south of the country, with Oaxaca the worst affected state.
The quake has hit at a time when Mexico is already reeling from the coronavirus pandemic.
It has suffered more than 22,500 COVID-19 deaths -- the second most in Latin America -- and 185,000 cases.
Medical staff were evacuated from some hospitals in the capital alongside patients, although those suffering from the coronavirus remained isolated inside the buildings, alongside their carers.
"All those that are in an area with COVID patients remain inside, only those of us who weren't there at the time" have come out, said Jaime Gomez, a nurse at a hospital caring for coronavirus patients.
Many of the people that fled into the streets of the capital were wearing face masks.
"With all the virus problems and now the tremors, and I've just lost one child and the other is ill, so imagine (how I'm feeling)," a tearful Maria Teresa Duran, 80, told AFP.
The quake took many people by surprise in the capital, including some working from home due to virus lockdown measures.
"We were working in our pyjamas, finishing off breakfast and then we had to get out like this," said 29-year-old Sonia Flores Cano.
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