Attackers drove a car into a government building in China's unruly far western region of Xinjiang on Wednesday and set off an explosive device killing one person, while all four of the attackers were shot dead, the regional government said.

Hundreds of people have been killed in recent years in resource-rich Xinjiang, on the borders of central Asia, in violence between the Muslim Uighur people who call the region home and ethnic majority Han Chinese.

The government has blamed the unrest on Islamist militants, though rights groups and exiles say anger at Chinese controls on the religion and culture of Uighurs is more to blame for the unrest. China denies any repression in Xinjiang.

The Xinjiang government said in a short statement on its main news website the incident occurred just before 5 p.m. (0900 GMT) in Karakax county, deep in southern Xinjiang's Uighur heartland.

It said the four "thugs" drove a vehicle into a yard at the county Communist Party offices and detonated an "explosive device", but were all shot dead.

Three people were wounded and one other died, it said, without giving details.

"At present, local social order is stable," the government said.

In a separate English language report, the official Xinhua news agency described the incident as a "terrorist attack".

State television said the attackers also used knives against staff at the party offices, and that the person they killed was a security guard and three government officials were wounded. It did not say if the guard died in the blast or the knife attack.

It is difficult for foreign journalists to report in Xinjiang, making it almost impossible to reach an independent assessment of security there.

Dilxat Raxit, a spokesman for the exiled group the World Uyghur Congress, said he doubted the official account."I strongly doubt the casualty toll and reason for the incident from official reports, which lack transparency," he said in an emailed statement.

The government has delayed reporting some previous incidents.

An attack on a coal mine in September last year, in which at least 16 died, was not reported by the government until two months later, when it announced its security forces had killed 28 of the "terrorists" involved.

Xinjiang had generally been quiet this year, with no major reported attacks or other violent incidents.