BEIJING (CNN) -- Clashes in the unsettled western Chinese region of Xinjiang killed 21 people, including police officers and local officials, authorities said Wednesday.The attacks took place Tuesday afternoon after three local officials visiting homes in the area found "several suspicious persons" and knives in one house, the Xinjiang government said in a statement.
When the officials alerted their superiors of the situation, the people in the house took them hostage, the statement said. Police rushed to the scene, and in the ensuing violence, six of the assailants and 15 other people were killed, it said.
Police captured eight of the attackers, whom the government described as "mobsters." It described the violence a "terrorist act," but did not elaborate why.
Xinjiang has been hit by periodic bouts of unrest. The worst violence in decades took place in July 2009, when rioting between Uyghurs and Han Chinese left around 200 people dead and 1,700 injured in the regional capital, Urumqi.
Uyghurs are predominantly Muslim ethnic Turks who are linguistically, culturally and religiously distinct from China's majority Han population.
Chinese authorities have cracked down on those they accuse of fomenting unrest in the region.
As is often the case, the government statement about Tuesday's clash didn't specify the ethnicity of the assailants. But it said that the 15 people killed who weren't "mobsters," comprised 10 Uyghurs, three Han, and two Mongolians.
The latest violence occurred in Bachu County, east of the city of Kashgar.