The U.S. Geological Survey (USGS) said the first earthquake was felt as far away as neighbouring Colombia. The agency initially reported it as magnitude 8, then revised it to 7.6 and later to 7.7. A second earthquake of magnitude 6.6 followed, along with multiple aftershocks.
In Panama City, visibly shaken residents gathered outside as they awaited news of the quake's impact. Rosendo Domínguez, a 60-year-old from Herrera province, told the Associated Press by phone: "We felt it very strongly. It knocked things over in the kitchen, but we're OK, though we're very scared. Everyone is outside, scared."
Multiple aftershocks continued to rattle Panama, including several measuring magnitude 5.8, 5.5 and 5.2. Seismologists at the University of Panama recorded more than 45 aftershocks, though many were too weak to be felt.
Authorities have not yet released a full assessment of casualties or structural damage, but buildings near the epicentre in Herrera province were reported to have collapsed.