Chinese state-media say about two-thousand people have attacked a government office in northwest China, smashing cars and beating police and officials.
The official Xinhua news agency says the rioters were protesting the forced demolition of homes and eviction of tenants in Gansu province's Longnan city.
A statement from the Longnan city government says some 30 petitioners, upset about the property dispute, were joined by hundreds of others.
The city says police, were met with a hail of rocks, bricks and flower pots after they decided to use force to break up the protest. The statement says police were also attacked by people with iron bars, axes and hoes.
Sixty officials were seriously injured during the riot.
The statement did not provide many details about the land dispute. Government-backed land grabs have long been a sensitive issue in China and are frequently the source of social tension and a trigger of protests.