At the hospitals of Nicoya and Liberia, in Guanacaste, hundreds of people packed emergency rooms seeking treatment for shock and minor injuries.
One death was confirmed, a man who died of a heart attack caused by fright, said Carlos Miranda, a Red Cross worker in the city of Liberia.
Douglas Salgado, a geographer with Costa Rica's National Commission of Risk Prevention and Emergency Attention, said a landslide hit the main highway that connects the capital to the Pacific coast city of Puntarenas, and hotels and other structures had cracked walls and items knocked from shelves.
In the town of Hojancha, a few miles (kilometers) from the epicenter, city official Kenia Campos said the quake knocked down some houses and landslides blocked several roads.
"People were really scared ... We have had moderate quakes but an earthquake (this strong) hadn't happened in ... years," she said.
In the last four decades, the region has been rocked by 30 earthquakes of magnitude-6 and larger. Two exceeded magnitude-7 — in 1978 and 1990 — but did not cause any deaths.
The last deadly quake to strike Costa Rica was in 2009, when 40 people died in a magnitude-6.1 temblor.
Associated Press writer Danica Coto reported this story in Congrejal and Cesar Barrantes reported in San Jose. AP writers Jack Chang, E. Eduardo Castillo, Olga R. Rodriguez, Santiago Torrado and Anita Snow in Mexico City and AP Science Writer Alicia Chang in Los Angeles contributed to this report.
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