The first quake, along with its powerful aftershocks, collapsed roofs, cut telecommunication lines and damaged a major highway to the provincial capital.
Reports from the area say buildings shook for about a minute. Chinese authorities put the quake at 6.6, but the U..S Geological Survey said it was a shallow 5.9 magnitude tremor that struck at about a half-a-mile deep.
Heavy rains have hit western china in recent weeks, causing floods like this that took out a bridge.
Authorities blame the rains and high waters for hampering rescue efforts. And forecasters say to expect more rain and possible landslides in the quake area.
Chinese authorities say the quake injured nearly 600 people, and close to 20 people cannot be found.