Guijie, the prominent dining street on Dongzhimen Inner Street in Beijing, was the scene of a terrifying brawl on Sunday around 5:30 pm, according to the description on the above video, recently uploaded by Ai Weiwei. There are scant details, but the description also says the fight was between Han Chinese and Tibetan street peddlers/stall-keepers. There are lots of projectiles.
— 艾未未Ai Weiweiさん (@aiww) 2013年5月12日
Just past the two-minute mark, we see a woman lying on the ground, probably unconscious, as a girl holds up her hand and cries hysterically.
More details as they become available.