China’s official Xinhua news agency says police in an ethnically-tense northwestern border region killed four suspects Sunday, following rioting Saturday night that left at least seven people dead and some 30 others wounded.

Details remained sketchy late Sunday, and Xinhua did not identify the suspects or say whether the violence in Kashgar is linked to ongoing tensions between local anti-Chinese Muslim Uighurs and China’s dominant Han ethnic group. More than 200 people have been killed in fighting between the two groups in the Xinjiang region since 2009.

Police on Sunday are quoted as saying four other suspects were captured in a manhunt that began late Saturday, when two knife-wielding men attacked a crowd in the city. Authorities say four others are being sought. Earlier reports said at least three people were killed in an explosion Saturday in the city, but Xinhua later reported the three were hacked to death by the attackers.

It is not possible to independently verify claims of either ethnic group, because it is difficult for outsiders to visit Xinjiang and the Chinese government maintains tight control of telecommunications in the region.

Earlier this month, Chinese authorities said police killed 14 people during a battle with Uigher protesters who seized a police station and killed four people in Xinjiang’s Hotan city.

The Xinjiang region is home to millions of Muslim Uighurs, who are angry with what they say has been decades of repressive rule by Beijing and the unwanted immigration of China’s dominant Han ethnic group.