Eight of the attackers were killed by police and three died when suicide devices they were carrying exploded, Xinhua, the official government news agency, reported.
Investigators said the group, described as terrorists, used motorbikes and cars in their attack on a police patrol at about 4 p.m. They were allegedly armed with knives and with gas canisters rigged to explode.
The attack took place in Wushi County of Aksu prefecture. Two police officers and two bystanders were wounded and five police cars damaged.
A similar incident occurred Jan. 24, when police said they shot six terrorists in an attack on a police station in Xinhe County.
About 43 percent of the population of the region is Uighur and 41 percent Han Chinese, and the area is majority Muslim. Authorities say violence has increased in the region since 2011.