About 447 aftershocks were reported following the 7.5 degree quake that shook Oaxaca, Mexico City and other states that left six deaths and material damages, the Civil Protection Coordination informed.
The U.S. Geological Survey (USGS) said the natural disaster measured 7.4 on the Richter scale, and it hit at 10:29 a.m. local time (11:29 a.m. EDT). The epicentre was 12km (seven miles) south-southwest of Santa Maria Zapotitlan in Oaxaca state.
Mexico President Andres Manuel Lopez Obrador said a building collapse in Huatulco killed one person and injured another. Otherwise, he said reports were of minor damage from the magnitude 7.4 quake, including broken windows and collapsed walls.
Oaxaca governor Alejandro Ismael Murat Hinojosa issued a statement indicating there 'are no damages.
In Mexico City, which is 190 miles north of the epicenter, residents were warned with the sound of seismic alarms as a signal to exit the building.
Helicopters hovered over downtown, and police patrols sounded their sirens.
The regions with a tsunami threat forecast include the coastal areas of Mexico, Guatemala, El Salvador, and Honduras, the release stated.
The national Civil Protection Center reported shortly before midnight that a sixth fatality had been registered in the southern state of Oaxaca, where at least 500 homes were damaged and colonial-era government buildings showed cracks. "Brothers and sisters, I am very close to you", he said. Smaller waves were expected through Central America, Peru and Ecuador.
Earlier estimates put the magnitude of the tremor at 7.7, but it was revised down to 7.4 on the Richter scale. The mayor of Mexico City, Claudia Sheinbaum, explained neither the city's safety command center nor officials conducting overflights of the municipality had reported any "serious" impacts from the natural disaster.
Mexico's Pacific coast is located along the seismically active "Ring of Fire", an area of fault lines that encircles the Pacific Ocean.