The injured, including two people in serious condition, have been sent to local hospitals, state-run Xinhua news agency reported.
"Many people ran out of buildings when the quake came, but there was no falling debris. The shopping mall resumed business shortly after," a mall shopper in the county said.
Rescue work is underway and local civil affairs authorities have dispatched relief materials such as tents and quilts to the area, the county government said.
The quake was followed by two more in Sichuan Province that both registered above magnitude 4.
A 4.5-magnitude quake jolted Yibin City, Sichuan Province, at 3:55pm, and another 4.7-magnitude quake hit Mianyang City at 10:17pm, according to the China Earthquake Networks Center.
Casualties and damages from the two quakes are not yet known.