One of the attackers was later killed in the violence that erupted Saturday night in a food street in Kasghar city, while another was detained, Tianshannet.com, a website operated by the regional government, said.
The report said the two attackers hijacked a truck that was waiting at a red light, killed the driver and ploughed the vehicle into passers-by on a nearby pavement.
They then got off the truck and began stabbing people at random, leaving six bystanders dead and another 28 injured before the crowd turned on them, killing one attacker. The other was detained, the report said.
Police in Kashgar would not comment when contacted by AFP.
The attack is the latest bout of unrest to hit China`s restive, northwestern region of Xinjiang, where Uighurs -- a mainly Muslim ethnic minority -- have long seethed against Chinese rule.
Earlier this month, more than 20 people were killed in a violent clash with police in the remote city of Hotan.
State media quoted an official in Xinjiang as saying that clash was a "terrorist" attack, adding that four people including a police officer were killed when a crowd set upon a police station.
But Uighur activists called it an outburst of anger by ordinary Uighurs and said security forces beat 14 people to death and shot dead six others during the unrest.
It was unclear whether Saturday`s attackers were Uighur.
Xinjiang has been plagued by violent unrest in recent years, culminating in savage Uighur attacks on members of China`s dominant Han group in the regional capital Urumqi in July 2009.(*)