(CNN) -- Four people, including two police officers, were killed Monday after assailants attacked a police station in the northwestern Chinese province of Xinjiang, the state-run Xinhua news agency of China reported.
The group attacked a police station in the city of Hetian, kidnapping six hostages and setting fire to the building, the news agency said.
Police officers opened fire on the attackers and rescued four hostages, Xinhua reported. Two police officers were killed and one was seriously injured while two hostages died, according to the news agency.
Investigators with an anti-terrorism unit will conduct an inquiry, Xinhua said.
The province of Xinjiang was the site of ethnic violence in 2009 that killed nearly 200 people and injured 1,800 others. Authorities blamed independence-seeking members of the Uighur ethnic group, a minority group of Turkic-speaking Muslims.
The 2009 violence came after long-simmering tensions between Uighurs and ethnic Han Chinese, who make up nearly 90 percent of China's 1.3 billion people.