A 5.6 magnitude earthquake struck Bulgaria’s capital Sofia early on Tuesday, causing residents to rush into the streets, the civil defense office said.

The quake, which occurred at 3 a.m. local time, shook apartment buildings and rattled windows but caused no casualties or damage, Nikolay Nikolov, an official from the office was quoted as saying by the national radio, citing initial reports.

The U.S. Geological Survey said the temblor was centered about 23 km (14 miles) west of Sofia and occurred at a relatively shallow depth of 9 Km (5.8 miles).

USGS initially reported the magnitude as 5.8.

A 5.6 magnitude earthquake struck Bulgaria's capital Sofia early on Tuesday, causing residents to rush into the streets

The civil defense office said the quake’s epicenter was near the western town of Pernik.

Pernik Mayor Rositsa Yanakieva told the national radio the quake caused chimneys to topple and an old house to collapse. Some 30 people in Pernik have sought medical help, complaining mainly of high blood pressure, she said.

Many people in the Bulgarian capital fled their homes and gathered in the streets.

“I’ve never experienced anything like this,” Ivanka Georgieva, who lives on the eighth floor in a residential block, told Reuters.

“It was very strong and it was frightening.”

The quake was felt across the southwestern part of Bulgaria.

The country of fewer than 8 million people lies in Europe’s earthquake-prone Balkan region.

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