A powerful natural disaster struck the South Korean city of Pohang on Wednesday, with local media reporting that resulting tremors were felt hundreds of kilometers away in Seoul.
Mark Zastrow, who lives in Seoul, tweeted: "Woah, natural disaster in Pohang and just felt it in Seoul, a few seconds after I got the alert on my phone".
The natural disaster shook South Korea's southeastern coast of Pohang.
Nuclear reactors in the region operated normally when the nation's strongest-ever natural disaster at magnitude 5.8 hit Gyeongju in September 2016.
No serious casualty was reported yet.
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According to local TV footage, some of the buildings saw external wall damaged and window broken.
Korea Hydro and Nuclear Power said nuclear power plants in the country are operating normally.
People evacuated buildings near the epicenter as soon as the felt tremors.
Tremors were felt in the South Korean capital Seoul, around 270km from Pohang, Yonhap added.
South Korean President Moon Jae-In, on his way to Seoul after attending the Asean summit in Manila, is set to hold an emergency meeting upon arrival, his office said.