Calls to the relatively autonomous provincial operators would not connect on Tuesday. A China Mobile spokeswoman said the company's Beijing office had not heard of an Internet blackout in Xinjiang.

Video of the riots posted on YouTube showed buildings burning, police or paramilitary troops running and hundreds of people streaming down streets. YouTube has been blocked in China for months.

China has long sought to restrict the expression of views that contradict official lines on and off the Internet. Chinese state media last month criticized Western cheering for Iranian activists who used Twitter to share information following contested elections.

Twitter is increasingly popular in China, but its user base is confined mostly to well-off urbanites.

The Xinjiang regional government blamed a global Uighur organization it labeled separatist for starting the riots, according to Xinhua. But injured people brought to one hospital included both Uighurs and members of the Han ethnicity, who make up the overwhelming majority in China, according to another Xinhua report.

Uighurs, mostly Muslims, speak a Turkic language and have more cultural similarities to central Asians than to Han Chinese.

The official death toll from the riots outstrips any unrest in China in many years.

"This is very big. The government always alters the death toll but this time the number came in astronomically high," said Wu'er.

"That can only mean one thing," he said. "This time it's brutal."