JUCHITÁN DE ZARAGOZA, Mexico — Thousands of homes in this city were severely damaged. Half of the 19th-century city hall, with its 30 arches, collapsed. The main hospital here was so devastated that staff members evacuated patients to an empty lot and worked by the light of their cellphones.

By the time the earthquake’s tremors finally faded, at least 36 people in Juchitán de Zaragoza were dead.

“It’s a truly critical situation,” Óscar Cruz López, the city’s municipal secretary, said Friday. “The city,” he said, and then paused. “It’s as if it had been bombed.”

Over all, the earthquake — the most powerful to hit the country in a century — killed at least 61 people in Mexico, all of them in the southern part of the country that was closer to the quake’s epicenter off the Pacific Coast.

The earthquake, which had a magnitude of 8.2 and struck shortly before midnight on Thursday, was felt by tens of millions of people in Mexico and in Guatemala, where at least one person died as well.