There was no immediate word on the chances of survival for the 30 to 40 people buried in the city of Dujiangyan, but rescue workers with search dogs had rushed to the area, the official Xinhua News Agency said.
Mudslides and flooding are common in China's mountainous areas, killing hundreds of people every year. Deforestation has led to soil erosion and made some parts of China prone to mudslides after strong rains.
In nearby Beichuan county, flooding destroyed buildings and destroyed exhibits at a memorial for the earthquake five years ago in Sichuan province that left 90,000 people dead or missing. The quake left the Beichuan county seat unliveable. The town was abandoned and 27 square kilometers (10 square miles) of ruins was turned into a memorial and museum.
The flooding also caused the collapse of an almost 50-year-old bridge in a neighboring county, sending six vehicles into the raging waters and leaving 12 people missing.
Since Sunday, flooding in Sichuan has affected 360,000 people, damaging or destroying 300 homes, and forcing at least 6,100 emergency evacuations, state media reported.
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