Guatemalans fearing aftershocks huddled in the dark and frigid streets of this mountain town wrapped in blankets early Thursday, while others crowded inside its hospital, the only building left with electricity after a powerful earthquake killed at least 48 people and left dozens more missing.

Crews worked through the night in San Marcos, searching rubble for survivors and more dead following the magnitude 7.4 quake that struck Wednesday near Guatemala's border with Mexico.

In the town of San Cristobal Cochu, firefighters picked at a collapsed house trying to dig out 10 members of one family, including a 4-year-old child, who were buried, fire department spokesman Ovidio Perez told the radio station Emisoras Unidas.

Volunteers carrying boxes of medical supplies began arriving in the area in western Guatemalan late Wednesday.

Eblin Cifuentes, a 26-year-old law student, and a group of his classmates already were collecting medical supplies as part of a school drive to provide aid for the only hospital in San Marcos, a poor, mainly indigenous mountain area of subsistence farms. When the quake hit, the group decided to bring everything they had collected.

"Thank God nothing happened to us and that's why we have to help out," Cifuentes said.

The quake caused terror over an unusually wide area, with damage reported in all but one of Guatemala's 22 states and shaking felt as far away as Mexico City, 600 miles (965 kilometers) to the northwest.

It hit hardest in San Marcos, where more than 30 homes collapsed and many of the colorful adobe buildings in its center were either cracked or reduced to rubble, including the police station and the courthouse. The temblor tore a large gash in one of the streets. Hundreds of frightened townspeople stayed in the open, refusing to go back inside after more than five strong aftershocks shook the area.

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.