Thousands of rescuers were deployed after some 40 homes were destroyed in Maoxian county, in what one local man said had been an "unprecedented" event.
At least 10 bodies have been recovered, but rescuers say they do not expect to find anyone else alive.
A couple and a baby were rescued and taken to hospital on Saturday.
Qiao Dashuai told state broadcaster CCTV that his baby had woken him and his partner in the early hours, adding that when the couple opened the door of their home they were swept away by water.
