The U.S. Geological Survey said the magnitude-6.9 quake was centered 268 kilometers (167 miles) east-southeast of Hotan at a depth of 10 kilometers (6.2 miles). The China Earthquake Networks Center measured the quake at magnitude 7.3 and said at least 20 smaller aftershocks ensued over the following two hours.
The epicenter was in Yutian county, a mountainous area several thousand meters above sea level on the edge of the Taklamakan desert. A magnitude-7.2 quake in that area in March 2008 collapsed some houses but caused no injuries.
China Earthquake Networks Center researcher Sun Shihong said any casualties from Wednesday's quake would likely be low.
The director of the Yutian Civil Affairs Bureau, Zhang Chong, said by phone that no casualties had been reported. A police officer in Yutian said he had felt tremors shaking the police station and ran outside.
Wang Gang, a fire brigade chief in Yutian County, told the national CCTV broadcaster he was heading from the county seat to the earthquake zone, about 100 kilometers (60 miles) away, with a team of police and firefighters.
Other officials interviewed by CCTV later said the quake had damaged mainly old houses in the area and that no casualties had been reported. The broadcaster showed footage of residents gathered in open spaces near apartment buildings that appeared largely undamaged.
China's worst earthquake in recent years was a magnitude-7.9 temblor that struck the southwestern province of Sichuan in 2008, leaving about 90,000 people dead or missing.