Riots in the city of Urumqi in the Xinjiang province in Western China have allegedly killed at least 156 people and injured an additional 800. Media access has been severely limited, making it very difficult for journalists to determine exactly what happened - but tensions between the Uighurs, an ethnic Muslim minority group, and the majority Han Chinese have been rising. Some news organizations have reports from witnesses that the Uighurs were protesting to demand for an official investigation into racially-motivated violence that erupted in the area in late June, but had been violently repressed by state police.
A few videos taken by eyewitnesses to the violence have been posted on YouTube:
And here is the official news report by government-controlled Chinese news service, CCTV: