27 people were killed in Chinas's Xinjiang Uighur autonomous region, where a large Muslim minority lives, said China's official news agency Xinhua.
Clashes broke out in the town of Lukqun, about 200 km southeast of Urumqi, the capital of Xinjiang on Wednesday.
A group of armed people with knives attacked a police station in Lukqun, the local government building and a construction site, said officials from Xinjiang regional Communist Party.
17 people were killed in clashes including civilians and police officers. After police opened fire ten other people were killed, increasing the death toll to 27.
Police have detained three people while the number of assailants is still unknown.
There have been clashes and violence in Xinjiang, where there is ethnic tension between Muslim Uighurs and Chinese settlers.
The Uighurs declared independence in October 1933 but the region went under the control of communist China in 1949. There has been immigration of Han Chinese, a majority ethnic group to East Asia, which subdued Uighur influence in the region and made them a minority. Muslim Uighurs have complained that China has restrained Uighurs' religious, commercial and cultural activities.