At least 25 people have been killed and large swaths of China's central Henan province were under water Wednesday, regional authorities said, after what some experts said was the region's heaviest rainfall in 1,000 years.

About 1.2 million people have been affected by the unfolding natural disaster, said Xu Zhong, a deputy director in the Henan local government responsible for flood and management. Seven people are missing, Xu said at a news conference.

Earlier, the Henan Information Office said four people died in Gongyi, a city by the banks of the Yellow River, adding to the 12 people who died when they were trapped in a subway train in Henan's capital, Zhengzhou, on Tuesday. Both cities suffered widespread collapses of homes and structures due to the rains.

Details have yet to be released about the locations, timing and circumstances of all of the deaths.