"Short-term extremely heavy rainfall" struck the towns of Taiping and Erlangping in Henan province between 9:00 pm and midnight on Monday, state news agency Xinhua said, citing the county emergency response centre.

A cumulative 225.3 millimetres (8.9 inches) of rain caused the local Shewei River to rise dramatically, "causing damage to some facilities and leaving people trapped", according to Xinhua.

"So far, two of the trapped people have been rescued, two have died, and six remain missing," it said.

It also said local authorities had launched a full-scale search-and-rescue mission in the stricken area.

China is the world's biggest emitter of the greenhouse gases that scientists generally agree are driving climate change and making extreme weather more intense and frequent.

But it is also a global leader in renewable energy, adding capacity at a faster rate than any other country.

Extreme weather has swept large parts of China in recent weeks, with six people killed and more than 80,000 evacuated due to floods in southern Guizhou province last week, according to state media reports.

Authorities issued heat warnings in Beijing last week as temperatures in the capital rose to nearly 40 degrees Celsius (104 degrees Fahrenheit).

Tens of thousands of people were evacuated last month in Hunan province, also in central China, due to heavy rain.