Yeouido Hangang Park is seen from Yeouinaru Station in Seoul, Thursday. Yonhap

Police are conducting a search at Yeouido Hangang Park in southern Seoul after a post online claimed that an explosive device had been planted in the area, sources said Sunday.

According to the Seoul Seongbuk Police Station, law enforcement received a report around 2:25 a.m. that a threatening post was written on a platform operated by a local broadcaster.

The writer claimed people at the park will be hurt unless authorities send 10 million won ($7,103) by wire payment, sources appraised of the situation said.

Currently, summer festival events are taking place at nine different parks along the river.