President Otto Perez Molina said that 40 people died in the state of San Marcos and eight more were killed in the neighboring state of Quetzaltenango.
Hundreds of people crammed into the hallways of San Marcos' small hospital after the quake seeking help for injured family members. Some complained they were not getting care quickly enough.
Ingrid Lopez, who bought in a 72-year-old aunt whose legs were crushed by a falling wall, said she had waited hours for an X-ray.
"We ask the president to improve conditions at the hospital," she said. "There isn't enough staff."
More than 300 firefighters, policemen and civilians dug desperately at a half-ton mound of sand at a quarry trying to rescue seven people believed buried alive. Among those under the sand was a 6-year-old boy who had accompanied his grandfather to work.
"I want to see Giovanni! I want to see Giovanni!" the boy's mother, 42-year-old Francisca Ramirez, frantically cried. "He's not dead. Get him out."
By Wednesday night, firefighters had dug out two bodies from the quarry, including Giovanni's.
Perez flew to San Marcos to view the damage in this lush mountainous region of 50,000 indigenous farmers and ranchers, many belonging to the Mam ethnic group.
"One thing is to hear about what happened and another thing entirely is to see it," the president told The Associated Press. "As a Guatemalan I feel sad ... to see mothers crying for their lost children."
Perez said the government would pay for the funerals of all victims in the impoverished region.
Efrain Ramos helped load a tiny casket carrying the body of his 6-year-old niece from San Marcos' morgue to a waiting pickup truck.
"The little girl died when a wall fell over her," a shocked Ramos told a reporter. He said the girl was playing in her room when the quake hit.