China’s military has blasted a dam to release floodwaters threatening one of its most heavily populated provinces, as the death toll in widespread flooding rose to at least 25.

The dam operation was carried out late Tuesday night in the city of Luoyang, just as severe flooding overwhelmed the Henan provincial capital of Zhengzhou, trapping residents in the subway system and stranding them at schools, apartments and offices.

Another seven people were reported missing, provincial officials said at a news conference.

See some of the damage in Zhengzhou after severe flooding:

Aerial images from cnsphoto and China Daily show the