Officials said the quake hit at 1:41 p.m. (1941 GMT) and was felt in Guatemala City, 125 miles (200 kilometers) to the south, where residents ran from homes and buildings.
Emergency officials in Mexico and Guatemala said they received no immediate reports of damage or injuries, although they were still investigating.
Telephone communication was spotty, likely because so many people immediately called to check on relatives.
"I'm really worried because I haven't been able to call my family," said Juan Carlos Calderon, a resident in Tuxtla Gutierrez, the Chiapas state capital. "I'm afraid because the building where I live is four stories high and very old."