Typhoon Chanthu killed at least three people before weakening into a tropical storm Friday after making landfall in southern China's Guangdong province.

Winds, which topped 120 kilometres per hour, knocked over a wall in the city of Wuchuan, killing two people, the official Xinhua news agency reported.

And flooding swept away a 50-year-old man in Hong Kong late Thursday. Marine police said they found his body in open water Friday morning.

Chanthu has moved north to Nanning, the capital of the Guangxi region, and has been downgraded to a tropical storm, the China Meteorological Administration said on its website.

The storm comes as China grapples with severe flooding that has left more than 700 people dead and over 300 missing so far this year, according to the flood prevention agency. The death toll is the highest since 1998, when more than 4,000 people died. Damage is in the tens of billions of dollars.

In Guangdong, floods have killed more than a dozen people and forced the evacuation of tens of thousands, Xinhua has said. Landslides triggered by heavy rain have crushed homes, and floods have wiped out crops across the province since June.

More torrential rain is expected across China this week, in provinces ranging from Yunnan in the southwest to Jilin in the northeast.