“It’s 71 (dead). Just for Oaxaca,” said Jesus Gonzalez, a spokesman for the state civil protection authority.
At least 15 people died in the neighbouring state of Chiapas, according to local authorities, while another four deaths have also been confirmed in the state of Tabasco to the north.
The 8.1 magnitude quake that struck off the coast of Chiapas on Thursday was stronger than a devastating 1985 temblor that flattened swathes of Mexico City and killed thousands.
Relief efforts in the south continued through the day with many of the people worst affected still wary of returning indoors to weakened buildings, fearing they could be brought down by ongoing aftershocks.
Meanwhile, anguished mourners lined the streets of the southern Mexican city of Juchitan which was devastated by the quake.
More than half of the known victims of the quake died in Juchitan, a picturesque, historic city near the coast where more than 5,000 homes were destroyed and many more left without running water or electricity.
In the Eighth Section neighbourhood, a working-class area where nearly every home was damaged, a loud drum and horn band played traditional music before the funeral of one of the dead.
The piercing blasts of the burly horn section at times were drowned out by the plaintive wailing of mourners for Maximo Zuniga, a little boy whose distraught relatives said was fond of his spiky black hair and bright red tennis shoes.
The three-year-old boy was asleep when the force of the quake brought his brick bedroom walls crumbling down on top of him, his mother and an older brother.
The boy died shortly after he was pulled from the rubble; the other two survived.
“I could barely see a little bit of his hair peeking out and his forehead,” said neighbour Alejandro Sanchez, who was the first to come to the stricken family’s aid. “There was a heavy wooden beam on top of all three of them and lots of dirt,” he added, as the dead boy’s uncle sobbed uncontrollably nearby.
The long, juddering tremor was felt some 800 km away in Mexico City and as far south as Honduras, but unlike the 8.0 magnitude quake in 1985 that killed thousands in the capital, outlying areas of Mexico were left relatively unscathed.
By contrast, much of the hot, muggy city of 100,000 near the Pacific coast looked as though it had been turned upside down.
Piles of rubble lay scattered across town, chunks of roofs littering the ground, and more than 300 locals were receiving care for injuries in area hospitals.
