The incident took place at about 8:00 p.m. on Thursday, when rioters attacked the seat of the Donggu township government of Garze County under the prefecture.

    "Local officials exercised restraint during the riot and repeatedly told the rioters to abide by the law," an official with the prefectural government said.

    But he said "police were forced to fire warning shots and put down the violence, since local officials and people were in great danger" and the rioters would not be persuaded to stop.

    The official, who is from the People's Congress of Garze County, was on an inspection tour when the riot broke out, he said.

    Local authorities are investigating the incident.