Rescue workers with search dogs are at the scene in the city of Djiangyan, Xinhua news agency reports. On Tuesday a bridge collapsed in the nearby city of Jiangyou, leaving at least 12 people missing.
Days of heavy rain and floods have damaged hundreds of homes and forced the evacuation of more than 36,000 people in Sichuan and Yunnan provinces.
Footage from Chinese state media, meanwhile, showed the dramatic rescue of a factory worker in the town of Deyang, who was stranded by the floods after the factory was washed away.
“The water level is so high that vehicles, forklifts and excavators have all been washed away,” Wei Xiao, another factory worker, told Reuters news agency.
Mud and landslides caused by flooding and strong rains are common in China’s mountainous areas, killing hundreds of people every year. Deforestation has also made soil erosion much more of a problem.
The landslide occurred in the town of Zhongxing is Dujiangyan – one of the places badly hit by the 2008 Sichuan earthquake.
The landslide, which covered about 2 sq km (0.8 sq miles), damaged at least 11 homes, Xinhua reported.
“So far we only know 11 families were buried and more than 200 residents have been evacuated,” a local official told AFP news agency.
Patrol members in Dujiangyan told local media that by the time they arrived at the scene, a few hours after the landslide, “everything was already a vast expanse of water”.
Eyewitnesses described stones and debris running down the hill and covering around eight homes in less than three minutes.
Meanwhile, rescue teams have been deployed in Jiangyou to search for those missing after Qinglian bridge collapsed, state media said.
At least six vehicles were reported to have plunged into the river when it came down after days of heavy rain.
Jiangyou’s local government say the river volume suddenly increased to a 50-year high on Tuesday.
“The high levels of flood sediment, and strong and destructive force of the water, caused the Qinglian bridge to collapse,” it said.
Two other bridges, one in Jiangyou and one in Deyang, were also washed away, officials said.
Chinese officials said that the heavy rain had affected more than 500,000 people in Sichuan and Yunnan provinces, damaged about 300 homes, and forced the evacuation of 36,800 people, Xinhua reported.
For the worst affected areas, it appears that there is going to be little respite, says the BBC’s Martin Patience in Beijing.
Heavy rainfall is forecast in Sichuan province over the next 24 hours, our correspondent adds.
In 2011, more than five million people were reported to be affected by deadly floods in eastern China.
In 2008, Sichuan was hit by a devastating earthquake which led to almost 90,000 people dead or missing. A swollen river has wrecked exhibits at a memorial to those who died.