BEIJING — Twenty-one people were killed and four others went missing due to the heavy rainfall affecting cities and counties in Hubei province, central China, said authorities Friday.

Hubei province's emergency and rescue center indicated that a number of areas were affected by rainfall, which began on Wednesday, adding that the level of rain reached 503 millimeters.

The heavy rainfall, revealed the center, impacted some 8,000 individuals. The center maintained that rescue efforts would continue to counter the situation.

The Liulin Township in Suixian County saw total precipitation reaching 503 mm from 9 p.m. Wednesday to 9 a.m. Thursday, causing an average waterlogging depth of 3.5 meters, the county said in an announcement.

Five cities in the central Chinese province of Hubei have declared "red alerts" after torrential rain, state media reported. Disaster relief and rescue efforts are under way.

China's National Meteorological Centre on Thursday issued a yellow alert, warning heavy rainstorms in some central and eastern parts of the country, calling for precautionary measures.

Heavy rains are expected on Friday in parts of Hubei, Anhui, Hunan, Jiangxi and Zhejiang, with up to 200 mm of rainfall in certain areas. Parts of the five provinces are likely to encounter over 80 mm of hourly precipitation accompanied by thunderstorms and gales.

The national observatory has advised local authorities to remain alert for possible flooding, landslides and mudslides, and recommended halting outdoor activities in hazardous areas.

China has a four-tier color-coded weather-warning system, with red representing the most severe warning, followed by orange, yellow and blue. Over 300 people were killed and 50 were listed missing when heavy floods ravaged Henan province and its provincial capital Zhengzhou city last month. — Agencies