Diana Marcela Troncoso, a biomedical engineer, was just one of more than 200 people feared trapped alive on Tuesday in the rubble of Cali, the city perhaps hardest hit by the earthquake that rocked Colombia a day earlier.

As emergency workers labored to find buried victims elsewhere in the city, firefighters from the capital, Bogotá, were able to extricate Ms. Troncoso, who is 31.

To get to her, firefighters had to make their way through a narrow tunnel under over 20 feet of rubble. On the surface, it was over 94 degrees Fahrenheit. In the tunnel, it was even hotter, and electrolyte drinks were kept close at hand.

A crowd of onlookers cheered on the rescuers. They could hear a newly freed Ms. Troncoso cry in pain when she was strapped to a backboard. Then they watched as firefighters carefully navigated the debris field and delivered her to a waiting ambulance.

But with the first 48 hours after a disaster like the quake considered critical, the rescue workers could not afford to linger.

Genevieve Glatsky contributed reporting from Cali, Colombia.