The temblor was downgraded from a 6.8. It hit around 10 a.m. in the southern Guerrero state about 188 miles southwest of Mexico City, and had a depth of 6.2 miles, the U.S. Geological Survey said.
There were no immediate reports of damage or injuries. There was only mild shaking in the resort city of Acapulco, according to an Associated Press reporter there.
DEVELOPING: We will add more details to this report as they become available.
The Associated Press contributed to this report.