Ethnic group drove a three-wheeled vehicle laden with explosives into a crowd of people, according to the words of a local government official.
All the casualties were local residents and authorities are still verifying their identities and ethnic backgrounds, he added.
The accident happened in west part of Xinjiang. The explosion took place around 10:30 am on the outskirts of Aksu city.
Police have determined it was an intentional act.
Long-simmering ethnic tensions between Han Chinese and native Uighurs in Xinjiang, who are Turkic-speaking Muslims, erupted into street riots in the provincial capital of Urumqi in July 2009, killing almost 200 people and injuring more than 1,800.