Rainstorm-triggered floods have affected 16,900 people in Ya'an City, southwest China's Sichuan Province. [Photo/Scol.com.cn]

Rain-triggered floods also caused a landslide in the village of Shilibei, as well as cut telecommunications and access to roads in many townships in Beichuan.

The Beichuan county government has relocated 2,019 residents as a precaution.

At the Shuangliu International Airport in the provincial capital of Chengdu, 4,000 passengers have been stranded, as more than 23 inbound and outbound flights have affected by the weather.

The Sichuan Provincial Meteorological Center has upgraded its orange rainstorm alert to red, with torrential rain and thunder expected in Chengdu, Ya'an and Deyang.

China has a four-tier color-coded warning system for severe weather, with red being the most serious, followed by orange, yellow and blue.

In neighboring Gansu Province, three villagers remain missing after falling into raging floodwaters Monday evening. Search and rescue efforts are under way.

Authorities in the city of Longnan issued a yellow alert for heavy rain early Tuesday, as the rain has been pounding the city since early Monday.

Local authorities also warned of the risk of potential geological disasters.