The vast western desert region – home to 10 million members of the mostly Muslim Uighur ethnic minority – last saw such bloody clashes in 2009, in riots that left hundreds dead.
Some in the Uighur community have blamed the unrest on economic inequality and religious repression, but China rejects these claims, pointing to investment in the resource-rich region and often pinning clashes on “terrorists”.
The Xinhua state news agency described the latest riot as a “terrorist” incident in which mobs attacked police stations and other sites before officers opened fire, leaving 35 dead including 11 rioters.
A further 21 police and civilians were injured and four rioters detained in the incident which occurred in Turpan city’s Lukqun township, the report said.
The World Uyghur Congress, a group run by Uighurs in exile, said in statement that the incident was “evidence of China’s failed policies towards Uighurs”.
It added that “an information blackout and security crackdown” in the area raised questions about state media’s version of events.
Police at a checkpoint 40 kilometres (25 miles) from Lukqun barred AFP journalists from entering on Thursday, citing safety concerns and ongoing investigations.
Xinhua said on Friday that the situation in the area was now “generally stable”.
Xinjiang propaganda officials and the Turpan police contacted by AFP declined to comment, referring queries instead to reports by Xinhua.