BY DANICA COTO

The Associated Press

CANGREJAL, Costa Rica

--A powerful, magnitude-7.6 earthquake shook Costa Rica and a wide swath of Central America on Wednesday, collapsing some houses, blocking highways and causing panic and at least one death from a heart attack.

Costa Rica President Laura Chinchilla announced there were no reports of major damage and called for calm.

At the epicenter, the beach town of Cangrejal, Jairo Zuniga, 27, said everything in his house fell when the quake hit at 8:42 a.m. local time.

"It was incredibly strong. I've felt earthquakes, but this one was 'wow,'" he said.

The U.S. Geological Survey said the quake was centered about 38 miles from the town of Liberia and 87 miles west of the capital, San Jose, where frightened people ran into the streets.

The magnitude initially was estimated at 7.9, but was quickly downgraded. Local residents said it shook for about 30 seconds and was felt as far away as neighboring Panama and Nicaragua, where school was canceled in some areas.

Officials initially warned of a possible tsunami, and local police supervisor Jose Angel Gomez said about 5,000 people--80 percent of the population--had been evacuated from coastal towns in the Samara district west of the quake's epicenter. But by mid-day they were allowed to return.

Panama also briefly called for people to evacuate beach areas.

In Costa Rica, one man died of a heart attack caused by fright, said Carlos Miranda, a Red Cross worker in the city of Liberia.