A powerful 6.8 magnitude earthquake slams Mexico only days after a fatal tremor.

Mexico City: A magnitude 6.8 earthquake rocked Mexico early Thursday, rocking skyscrapers in Mexico City, just days after another powerful tremor killed two people and damaged hundreds of structures.

Residents of Mexico City fled their houses as the earthquake alert rang and buildings shook.

Soon after, Mexico City Mayor Claudia Sheinbaum tweeted that there had been no immediate reports of damage in the city.

The quake, which was initially recorded at magnitude 7.0 by the US Geological Survey (USGS), occurred at a depth of 20.7 km (12.9 miles), which was somewhat deeper than Monday's tremor.

A magnitude 7.6 earthquake struck western Mexico on Monday, the anniversary of terrible earthquakes in 1985 and 2017, killing two in the Pacific city of Manzanillo.