Heavy rainfall forced the subway system in Zhengzhou, capital of China's Henan province, to shut down Tuesday, stranding passengers.
Riders posted videos on social media as they awaited rescue in waist-high muddy waters. A passenger named Xiaopei posted on Weibo that "the water in the carriage has reached (their) chest."
Around 300 people have been rescued so far, and an unknown number remain trapped.
Local media outlets report that train floodwaters were lowering.
Henan province, home to about 94 million people, experienced severe rains through the past week. On Tuesday, the region's meteorological station issued the highest threat level, a red warning, as rains are expected to continue for the next 24 hours, Reuters reported.
A representative of the city of Xu Liyi, a member of the Standing Committee of Henan Provincial Party Committee, and Secretary of the Zhengzhou Municipal Party Committee said the high levels of rainfall were unusual.
Extreme weather events have surged this summer in China, with recent flooding in Sichuan province killing hundreds of citizens and forcing thousands to evacuate the area. Officials of Greenpeace International, an environmental group, warn that China's rapid urbanization will increase the frequency of climate disasters.
Speaking to the Chinese media, Liu Junyan of Greenpeace said "because of the highly concentrated population, infrastructure and economic activity, the exposure and vulnerability of climate hazards are higher in urban areas."
This report contains information from Reuters.