A 7.8-magnitude earthquake rattled Ecuador's central coast Saturday night, killing at least 233 people and injuring nearly 1,500. Buildings collapsed, and power was knocked out for millions. The death toll is expected to rise as rescue workers comb through the damage.

A tsunami alert was issued, then lifted. Several provinces remain in a state of emergency, however, including Guayas, Manabi, Santo Domingo, Los Rios, Esmeraldas, and Galapagos.

The earthquake was centered 16.8 miles (27 kilometers) southeast of the coastal town of Muisne, according to the U.S. Geological Survey.

It was most likely the result of shallow thrust faulting on or near the boundary between the Nazca and Pacific plates, the science agency reports. At that location, the Nazca plate subducts eastward beneath the other plate, at a rate of about 2.4 inches (61 millimeters) a year. Movement in this region has led to the uplift of the Andes and the largest earthquake on record, the 1960 magnitude 9.5 temblor in southern Chile.

This weekend's event was the deadliest to strike Ecuador since March 1987, when a 7.2-magnitude earthquake killed 1,000 people. (Learn about Japan's recent earthquakes.)