The natural disaster of magnitude 8.1 quake, which was felt as far as Mexico City and Guatemala City, was also registered off Mexico's southern coast just as heavy rains from Hurricane Katia lashed the east.
President Enrique Peña Nieto said this quake was the strongest the country has seen in almost a century.
"We are assessing the damage, which will probably take hours, if not days", said Mexican President Enrique Peña Nieto, in an address to the nation about two hours after the quake.
A huge rescue operation was under way in the worst-hit states of Tabasco, Oaxaca and Chiapas where people are feared trapped under the rubble, BBC reported.
The USGS says there have been more than thirty aftershocks, ranging from 4.2 to 5.7 in magnitude.
President Enrique Pena Nieto ordered schools to remain closed Friday in Chiapas and Mexico City so officials could inspect for structural damage. It had a depth of more than 40 miles. The earthquake's epicenter was 120 kilometers offshore in the Pacific Ocean, 1,000 kilometers southeast of the capital.
It's said to have lasted just 95 seconds, but killed at least 400 people in both Mexico and Guatemala. In 1985, a magnitude 8.0 quake struck the capital, killing thousands of people and damaging thousands of buildings. He said three people died in the town of San Cristobal, including two women who perished when the wall of a house collapsed on them.