The unrest began when a peaceful protest by Muslim ethnic minority Uighurs turned violent after it was stopped by police. The Uighurs went on a rampage, smashing windows, burning cars and beating Han Chinese, the nation's dominant ethnic group.
Two days after the first rioting, vigilante groups of ethnic Han took to the streets and attacked Uighurs.
Xinjiang Governor Nur Bekri said police shot the "mobsters" after first firing warning shots, according to a report late Saturday by the official Xinhua News Agency. He apparently did not say which ethnic group the "mobsters" belonged to.
"The police showed as much restraint as possible during the unrest," Bekri was quoted as saying, adding that many police officers were injured, while one was killed.
An official surnamed Wu from the Xinjiang regional government information office confirmed the report Sunday. Wu could not say if those killed by police were Uighurs or Han Chinese.
The governor said three of them died on the spot and nine died after treatment failed.
The government first acknowledged that its security forces had opened fire more than a week after the rioting started, when police shot dead two Uighurs and wounded a third July 13. An Urumqi official said the Uighurs started fighting with police after officers tried to stop them from attacking a fellow Uighur.
In Saturday's Xinhua report, Bekri also said the death toll from the unrest had risen to 197. The government had previously said the rioting killed 192 and injured 1,721.
Authorities accuse Rebiya Kadeer, a prominent exiled Uighur activist, of inciting the unrest. They have not provided evidence, and Kadeer, who lives in the U.S., has denied it.
The initial protest was centered on calls for an investigation into the June 25 deaths of Uighur factory workers killed in a brawl with Han Chinese in the southern city of Shaoguan. State media reports said two people died.
Graphic photos, however, soon spread on the Internet purportedly showing at least a half dozen bodies of Uighurs with Han Chinese standing over them, arms raised in victory.
By Associated Press Writer Gillian Wong