A road is flooded in the urban area of Xinyi, Guangdong province.[Photo/ycwb.com]

GUANGZHOU - An extremely rare round of torrential rainfall that happened once in more than 200 years hit a city in south China's Guangdong Province, local authorities said Saturday.

Xinyi, a small, county-level city in Maoming, saw 429.5 millimeters of rainfall in just six hours, according to the provincial flood control and drought relief headquarters.

Eight people died and four others were reportedly missing in Xinyi.

The provincial civil affairs department has declared the second highest state of emergency and dispatched working teams to Xinyi.

Relief supplies including 200 tents and 10 tonnes of rice have been sent to the disaster-hit areas.

The rainstorm abated on Saturday afternoon and stopped in the evening. But local authorities still warned of geological disasters in mountainous areas.