The attack was part of a disagreement between residents of Gansu province and the vast Inner Mongolia region it borders to the north, state newspapers reported.
China's government regularly cites such incidents as justification for heavy-handed Communist Party rule. Often driven by economic or ethnic rivalries, such incidents stretch the capacity of local law enforcement bodies to cope, especially in the relatively impoverished west.
More than 100 men with their faces covered descended on the Ejin Banner office complex at about 3 a.M. On Sunday, the Ejin Banner county government said on its website.
They were hooded, threatened, beaten with clubs and dumped outside where temperatures were about -20 Celsius (-4 Fahrenheit), the government said. Six men were taken to hospital for treatment.
Photos on the website showed demolished pre-fabricated structures and pick-up trucks crushed from being flipped over.
The Ejin Banner government said the attackers used two bulldozers to carry out the destruction and also stole any personal or government property they could find.
Reports said the attack likely grew out of a long-running dispute over land rights in Ejin Banner, which had been part of Gansu until it was returned to Inner Mongolia in 1979. No suspects have been named publicly.
