People walk through heavy downpours in Jongno District, Seoul, Wednesday. Yonhap

A heavy rain watch was issued across parts of northern Gyeonggi Province on Wednesday, with 100 millimeters of rain per hour pouring in the border city of Paju, the state weather agency said.

As of 7 a.m., heavy downpours of 100.9 mm per hour had been pounding Munsan, a town in Paju, 37 kilometers northwest of Seoul, according to the Korea Meteorological Administration (KMA).

The accumulated precipitation was recorded at 342.5 mm in the inter-Korean border village of Panmunjom, 202 mm in Namyangju, 181.5 mm in Yeoncheon County and 159.5 mm in Seoul's Nowon Ward between 5 p.m. Monday and 11 a.m. Wednesday.

The downpour was especially prominent in Uijeongbu, where 103.5 mm of rain poured per hour as of 8:22 a.m., and Paju, which received 101.1 mm of rain per hour at around 7 a.m.

The KMA sent out emergency text alerts warning of torrential rain across Seoul and the northern part of Gyeonggi Province on 20 occasions between 4:24 a.m. and 9:40 a.m., in what marks the first time this year such a warning has been issued in the greater Seoul area.

Heavy rain alerts are issued when the rainfall exceeds 50 mm per hour and 90 mm over a three-hour period, and in cases where the hourly precipitation rate exceeds 72 mm.

Cheonggye Stream is flooded by heavy downpours in Jongno District, Seoul, Wednesday. Yonhap

In South Jeolla Province, 161 cases of flooding in homes, as well as a total of 10 cases of landslides and destruction of roads, were reported, and in Gyeonggi Province, nine road disruptions occurred and two homes were temporarily flooded.

No casualties have been reported so far, officials said.

Over 300 trails from six national parks were cordoned off, and 48 passenger ships from 28 sea routes could not operate as usual due to inclement weather conditions.

The interior ministry activated the first stage of its three-stage response posture and raised the heavy rain alert to "caution," the second-highest level in the four-level system.

A heavy rain watch was issued across 10 cities and counties in northern Gyeonggi Province, with some regions forecast to receive up to 200 mm of rain until Thursday, the KMA said. (Yonhap)