The U.S. Geological Survey says a new earthquake which stuck Mexico Saturday had a magnitude of 6.1 and was centered in the southern state of Oaxaca.
It initially calculated as a magnitude 6.2 quake.
The director of Mexico's disaster agency says it's an aftershock of the 8.1 quake that hit on September 7 off the country's southern coast.
The new quake also swayed buildings in Mexico City, which is trying to recover from a magnitude 7.1 temblor that struck on Tuesday and has killed at least 305 people.
It's not immediately clear if the new quake caused any damage or injuries.
The Associated Press contributed to this report.