Some 40 homes in the village of Xinmo were swallowed by huge boulders after the side of a mountain collapsed, blocking a two kilometre (one mile) stretch of river.
Some 40 homes in the village of Xinmo were swallowed by huge boulders after the side of a mountain collapsed, blocking a two kilometre (one mile) stretch of river, according to a statement and images released by the Maoxian government.
Rescuers used ropes to move a massive rock while dozens of others scoured the mountain for survivors.
Bulldozers and heavy diggers were also deployed to remove boulders, the images showed. Medics were seen treating a woman on a road.
"There are several tonnes of rock," local police captain Chen Tiebo told the state broadcaster CCTV.
Chen said the heavy rains that hit the region in recent days had triggered the landslide.
"It's a seismic area here. There's not a lot of vegetation," Chen said.
Trees can help absorb excess rain and prevent landslides.
Some 500 people were taking part in rescue efforts, according to CCTV.
An emergency response "to the first class catastrophic geological disaster" is under way, the local government's statement said, adding that the full extent of the landslide was at yet unclear.
A report from the state news agency Xinhua said that the landslide came from a high part of a mountain in the Tibetan and Qiang Autonomous Prefecture of Aba had collapsed.
The landslide struck the village at around 0600 am local time (2200 GMT).
Landslides are a frequent danger in rural and mountainous parts of China, particularly at times of heavy rains.
At least 12 people were killed in January when a landslide crushed a hotel in central Hubei province.
In October landslides battered eastern China in the wake of torrential rains brought by Typhoon Megi, causing widespread damage and killing at least eight.
More than 70 were killed by a landslide in the southern commercial hub of Shenzhen in December 2015, caused by the improper storage of waste.