The U.S. Geological Survey said a magnitude 6.9 temblor struck an area in southern Qinghai, near Tibet, on Wednesday morning and was followed by several aftershocks.

The main quake sent residents fleeing as it toppled houses made of mud and wood, said Karsum Nyima, the Yushu county television station's deputy head of news, speaking by phone with broadcaster CCTV.

"In a flash, the houses went down. It was a terrible earthquake," he said. "In a small park, there is a Buddhist tower and the top of the tower fell off. ... Everybody is out on the streets, standing in front of their houses, trying to find their family members."

The quake hit the county of Yushu, a Tibetan area in Qinghai's south, said the China Earthquake Networks Center, which measured the quake's magnitude at 7.1. A local government Web site put the county's population in 2005 at 89,300, a community of mostly herders and farmers.