Beijing - Masked men attacked a government office in western China, smashing vehicles and equipment and leaving 13 people injured.
The incident early on Sunday morning was apparently sparked by a dispute between residents of Gansu province and the vast Inner Mongolia region it borders to the north.
Police and official reports said more than 100 men with their faces covered descended on the Ejin Banner office complex at about 03:00.
They used pepper spray on staff members and herders taking shelter, beat them with clubs and dumped them outside where temperatures were about -20 degrees.
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.