China has erupted into the deadliest ethnic riots Sunday since the 1989 military crackdown on the Tiananmen pro-democracy demonstrations.
The government has shut down the internet on Monday and blamed Sunday's riots in Urumqi on exiled Muslim separatists.
At least 156 people have been killed and hundreds of people have been arrested who are burning, smashing vehicles and shops and clashing with anti-riot police, the official Xinhua news agency reported Monday.
It was like a war zone here, with many bodies of ethnic Han people lying on the road, Xinhua quoted Huang Yabo, deputy director of the Urumqi Public Security Bureau saying.
I personally saw several Han people being stabbed. Many people on buses were scared witless, Zhang Wanxin, an Urumqi resident, said by telephone.
The unrest highlights the volatile ethnic tensions that have accompanied China's growing economic and political stake in its western frontiers.
Xinjiang is the doorway to China's trade and energy ties with central Asia, and is itself rich in gas, minerals and farm produce. But many Uighurs say they see little of that wealth.
Security officials said that many of the dead bodies were Han Chinese, suggesting an explosion of pending anger against the economically dominant group.
The United States urged all in Xinjiang to exercise restraint.
We are deeply concerned over reports of many deaths and injuries from violence in Urumqi in western China, said White House spokesman Robert Gibbs.