At least 10 people were hacked to death when mobs went on the rampage in the restive Xinjiang region yesterday evening, state media reported.
They attacked at about 6pm on Xingfu Street in Yecheng, Kashgar prefecture, witnesses were quoted as saying by Xinhua, adding that numerous others were injured.
The report said local police had shot dead at least two suspects and were chasing the rest, who had fled.
It could be the worst attack in terms of victims killed since the region's party secretary, Zhang Chunxian, took charge in April 2010.
Seven alleged mobsters were shot dead in the mountainous area of Hetian, or Hotan, prefecture after allegedly kidnapping two herders in late December last year.
Johnny Lau Yui-siu, a Hong Kong-based veteran China watcher, said that Yecheng county had long been a hotbed for violence, with several deadly incidents in the remote area in the 1980s and 1990s.
'It is impossible to guard against such unrest when deep-seated conflicts on both a political and economic basis remain there,' said Lau, adding that Yecheng was still an impoverished backwater area when he visited there two or three years ago.
'Many suspects are said to have received terrorist training in the region bordering Pakistan, in which they can hide themselves after committing crimes. This, in turn, makes it even more difficult for the Chinese authorities to get rid of them.'
However, Lau said he could not envision such violence harming Zhang's political prospects. 'At the moment, I don't think Zhang should be held responsible for the incident, because it is a rampage seemingly beyond his control,' Lau said.
Zhang told Hong Kong media last August that the government could not rule out further terrorist attacks in the region. 'It is impossible to expect terrorist attacks to disappear because of which official administers Xinjiang,' Zhang said.
It remains unclear whether the violence had anything to do with so-called foreign separatist and terrorist forces. However, that will likely become a focal point when the annual sessions of the Chinese People's Political Consultative Conference and National People's Congress open on Saturday and Monday.
As open-minded, politically moderate and media-savvy, Zhang is widely regarded as a rising star who will very likely get a seat on the Communist Party's top decision-making Politburo in the power reshuffle due to take place this autumn.
Zhang replaced the hardline Wang Lequan in taking his Xinjiang post in April 2010.
Officials in Xinjiang could not be reached for comment last night.
In Kashghar in August 2008, just days before the opening of the Beijing Olympics, at least 16 People's Armed Police officers were killed when two Uygurs rammed a truck into them before stabbing them when they were jogging outside their barracks.
And in August, two separate attacks in Kashgar in less than 24 hours left at least 14 people dead and 42 injured. That followed a July 18 terrorist attack targeting a police station in the city of Hetian that left 18 people dead, including 14 terrorists.
On July 5, 2009, Uygurs went on a rampage through the streets of Urumqi, attacking Han Chinese civilians. The government said at least 197 people were killed and more than 1,600 injured in the riots, most of them Han. Overseas Uygur groups say an unknown number of Uygurs were wounded or killed by security forces.