|This is the worst violence in the region since August 2010, when seven police were killed in clashes
At least four people died during a mob attack on a police station in western China's Xinjiang region, according to Chinese state media.
A mob invaded the police station in the city of Hotan, took hostages and set the building on fire, state broadcaster CCTV reported on Monday.
It said the situation has now been brought under control, with six hostages freed.
The official Xinhua news agency reported that one policeman, two hostages and a civilian died during the attack and that "a number of thugs" were shot dead by the police who rushed to the scene.
The Xinhua report did not give a reason for the mob's attack.
There was no official confirmation from neither the Xinjiang government nor the Hotan police, but an unnamed official at the information of Xinjiang Public Security Department in Urumqi, the province capital, confirmed the attack to the Associated Press news agency.
The official did not provide any details.
Chinese officials commonly refuse to identify themselves when speaking to the press.
Beijing often blames what it calls violent separatist groups for attack on police or other government targets, saying that they are linked to al Qaeda or Central Asian armed groups seeking to bring about an independent state called East Turkestan.
Uighurs are a largely Muslim, Turkic-speaking ethnic group that see Xinjiang as its homeland. Many Uighurs chafe under rule from Beijing and restrictions on their language, culture and religion. They resent the Han Chinese majority as interlopers.
Monday's violence was the worst the region has seen since last August, when seven Chinese military police were killed when a member of the Uighur minority rammed them with an explosives-laden vehicle in the Xinjiang border region.
In July 2009 Urumqi was rocked by violence between the majority Han Chinese and minority Uighurs that killed nearly 200 people.
Dilxat Raxit, the spokesman for the Germany-based World Uighur Congress, said that several sources in Hotan told his group that the police opened fire on a peaceful protest held earlier on Monday by a large group of Uighurs.
More than 100 Uighurs were demonstrating against alleged illegal seizures of Uighur-held land and to demand information about relatives who they said had disappeared amid a police crackdown that began after the 2009 riots in Urumqi, Dilxat said.