LA SERENA, Chile (Reuters) - A magnitude 6.7 earthquake hit the coast of north-central Chile on Saturday evening, the U.S. Geological Survey said, with authorities reporting as many as 200,000 without power and two people dead of heart attacks.

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The quake struck at 10:32 p.m. about 16 km (10 miles) south-southwest of Coquimbo, the USGS said. The quake, measured 53 km (33 miles) below the surface, shook homes, caused landslides in the region’s mountainous terrain and initially prompted authorities to begin a mass evacuation of coastal areas ahead of a potential tsunami.

The Pacific Tsunami Warning Center, however, quickly ruled out that threat.

An elderly man and woman died of cardiac arrest thought to be associated with the earthquake, according to police and local media reports.

The quake also knocked out a major power station, but electricity was restored to most of the region overnight.

A witness reported minor damage to older buildings in the coastal city of La Serena, a popular Pacific coast beach town about 400 kilometers (250 miles) north of Santiago.

“It felt very strong... The tourists were very nervous, but nothing serious happened,” Camila Castillo, a receptionist at a hotel in La Serena, told Reuters.

Chilean miner Antofagasta Plc said operations were normal at its Los Pelambres copper mine.

Chile, located on the Pacific “Ring of Fire”, has a long history of deadly quakes, including a 8.8 magnitude quake in 2010 off the south-central coast that triggered a tsunami that devastated coastal towns.

But death and destruction tend to be limited due to the adoption of strict construction codes.