Knife-wielding attackers killed 10 people in China's Xinjiang region and another four were shot dead by police as a wave of violence swept the ethnically-torn area, state media and officials said Sunday.

The unrest occurred in the ancient Silk Road city of Kashgar in two separate attacks, and local residents said Sunday the city centre was under lockdown, with security forces patrolling the streets.

Xinjiang has seen several outbreaks of ethnic violence in recent years as the mainly Muslim Uighur minority bridles under what it regards as oppression by the government and the unwanted immigration of ethnic Han Chinese.

Earlier this month, more than 20 people were killed in a clash with police in the remote city of Hotan.

In the first attack on Saturday evening, seven people were killed and 28 others hurt at a night market by two attackers with knives, one of whom was later killed in violence, the authorities said.

Hou Hanmin, spokeswoman for the government of the northwestern region, told AFP the attackers were both Uighurs, adding the suspect who was still alive had been detained.

"The case is still under investigation so I don't have more information," she said.

On Sunday three people were hacked to death by rioters, the official Xinhua news agency said. It had earlier reported they died in an explosion, but a follow-up report left it unclear whether there had been a blast or not.

Police shot dead four suspects allegedly involved in the attack and detained four others, Xinhua said, while another four were on the run.

Dilxat Raxit, a spokesman for the Germany-based World Uyghur Congress -- an exile group -- said security forces had shot dead six people and injured nine others on Sunday.

Xinhua said more than 10 bystanders and police officers were injured in the violence. The government spokeswoman was not available when contacted about Sunday's unrest.

The owner of a restaurant on a street where the violence occurred, surnamed Zhang, told AFP he heard an explosion near his establishment.

"I saw injured people being carried away on stretchers, and some customers in my restaurant were injured too," he said by phone.

"Many police came after the blast and the street is now blocked. People don't dare go out, and I won't go out tonight either."

According to tianshannet.com, a website run by the regional government, the suspects in Saturday's attack hijacked a truck that was waiting at a light at the food market in Kashgar, not far from the border with Kyrgyzstan.

They killed the driver, ploughed the vehicle into passers-by on a nearby pavement, then got out of the truck and stabbed people at random, leaving six bystanders dead before the crowd turned on them and killed one attacker.

Raxit cited local sources as saying the assailants had clashed with members of a civilian force that maintains public security.

He called for China to "immediately stop its long-term, systematic repressive measures... to prevent further unrest."

Raxit said at least 100 Uighurs had been detained following Saturday's incident.

Many Uighurs are unhappy with what they say has been decades of political and religious repression, and the unwanted immigration of China's dominant Han ethnic group.

While standards of living have improved, Uighurs complain that most of the gains go to the Han.

This tension has triggered sporadic bouts of violence in Xinjiang -- a vast, arid but resource-rich region which is home to more than eight million Turkic-speaking Uighurs.

State media quoted an official in Xinjiang calling the Hotan clash earlier this month a "terrorist" attack, adding that four people 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 killed 20 people during the unrest.

In the nation's worst ethnic violence in decades, Uighurs savagely attacked Han Chinese in the regional capital Urumqi in July 2009 -- an incident that led to retaliatory attacks by Han on Uighurs several days later.

The government says around 200 people were killed and 1,700 injured in the violence, which shattered the authoritarian Communist Party's claims of harmony among the country's dozens of ethnic groups.