MEXICO CITY - A powerful aftershock measuring 6 on the Richter Scale roused slumbering Mexico City residents and sent them into the streets in the early hours of Monday.

The aftershock was the strongest yet of some 2,140 aftershocks of varying intensity that have shaken south-central Mexico since Friday's major 7.2-magnitude earthquake, the National Seismological Service (SSN) said.

The magnitude 6 aftershock, which hit just a few minutes before 1 a.m. local time, sparked the citywide early-warning system, leading residents on lower floors to evacuate their homes.

Like Friday's quake, the epicenter was located off the coast of southern Oaxaca state, but the seismic waves were felt in as many as eight states, though no casualties or damage was reported.

The south-central region, including the capital, is still reeling from two powerful quakes that hit some two weeks apart in September, leveling buildings and killing more than 300 people.

Mexico lies atop five different tectonic plates, the Pacific, Rivera, Cocos, North American and Caribbean plates, making it highly quake prone.