The dissident Chinese artist Ai Weiwei has filmed a fight in China in which dozens of Han Chinese brawled with Tibetans in a street in Beijing.
The artist, who has exhibited at London's Tate Modern but has also had run-ins with Chinese authorities himself, caught the mass bust-up on camera on Sunday.
Witnesses said the scrap was between ethnic Tibetan street vendors and Beijing's native Han restaurant workers.
Police were filmed trying to control the men as they hurled chairs at each other in front of a restaurant on the capital's popular 'Ghost Street'.
Several were shown with bloodied faces.
Nearby, a young woman was shown standing next to an apparently-injured woman lying on the ground.
Once the fight had been mostly dispersed, officers struggled to prevent one group, who onlookers said were Tibetan, from hurling bricks, stones and chairs at the restaurant front.
Mr Ai, China's most famous contemporary artist, said he was out with his mother when he saw the brawl happening at around 5.30pm local time (0930 GMT).
He said the fight appeared to be between security guards at a Sichuanese restaurant and Tibetan vendors who sell jewellery on mobile stands.
Han Chinese witnesses told the Reuters newswire service that the fight had started when security workers refused to allow the vendors to sell on the pavement in front of their restaurant.
Restaurant workers refused to speak to Reuters, and it was not immediately possible to confirm the identities of anyone involved in the incident.
It was also unclear whether any brawlers were arrested or seriously injured.
The restaurant windows had already been replaced on Monday morning, and workers said they were "refurbishing".
Mr Ai was an artistic consultant on the Beijing National Stadium for the 2008 Olympics.
His artwork made up of thousands of sunflower seeds at the Tate Modern in 2010 was seen by an estimated 3.4 million people.
He has been openly critical of the Chinese government's stance on democracy and human rights. In 2011, he was held for more than two months despite no charges being filed.
The footage is just the latest incident in a long history of tension between Tibetans and Han Chinese.
Many of those living in Tibet feel deep resentment that the region, in China's south, is being occupied by ever-increasing numbers of Han migrants since the Chinese government moved to make travel there easier.
The Chinese government, based in the capital Beijing, regards Tibet as underdeveloped and has spoken of the need to increase the standard of living for those living there.