A 6.1 magnitude earthquake hit Sichuan province, in what was the strongest in a number of aftershocks to hit the country this week.
Earlier, thousands of people fled amid fears a lake would burst its banks in Beichuan, near the epicentre of China's earthquake.
People were told to flee to the hillsides in a public announcement.
An area in Qingchuan near the epicentre of the 7.9 magnitude earthquake was ordered to evacuate and people scrambled to higher ground.
The official Xinhua news agency said earlier the water level was rising rapidly and may burst its bank at any time.
There has been growing concern about the safety of dams and reservoirs which have been weakened in the mountainous province of Sichuan.
The government has raised the confirmed death toll by more than 6,000 to 28,881.
But many expect the eventual figure could surpass even the government's estimate of over 50,000.
Earlier, more survivors were plucked from the rubble as rescuers in battled to save lives five days after the huge quake.
With towns and villages reduced to a mass of twisted metal and concrete, recovery teams used sniffer-dogs and cutting equipment to try and find victims trapped under buildings across the southwestern province of Sichuan.
A German tourist was pulled out of the wreckage today by soldiers, after being buried for 114 hours.