BEIJING — Typhoon Chanthu killed three people before weakening into a tropical storm Friday after making landfall in southern China’s Guangdong province.

Winds of up to 78 miles per hour (126 kilometers per hour) knocked over a wall in Guangdong’s Wuchuan city, killing two people, the official Xinhua News Agency reported.

Heavy flooding swept away a 50-year-old man in a village 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 been downgraded to a tropical storm, the China Meteorological Administration said in a statement on its website.

The storm comes as China grapples with severe flooding that has left at least 742 people dead and 367 missing so far this year, the flood prevention agency said Friday. The death toll jumped by more than 40 Friday, but it was not clear if the increase was from new deaths this week.

This year’s floods are the deadliest since 1998, when more than 4,000 people died. Damages are 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 rains crushed homes and floods have wiped out crops across the province since June.

More torrential rains are expected across China this week, from Yunnan province in the southwest to Jilin in the northeast.