URUMQI, China — Violent street battles killed at least 140 people and injured 828 others in the deadliest ethnic unrest to hit China's western Xinjiang region in decades, and officials said today the death toll was expected to rise.

Police sealed off streets in parts of the provincial capital, Urumqi, after discord between ethnic Muslim Uighur people and China's Han majority erupted into riots. Witnesses reported a new protest today in a second city, Kashgar.

Columns of paramilitary police in green camouflage uniforms and flak vests marched today around Urumqi's main bazaar — a largely Uighur neighborhood — carrying batons, long bamboo poles and slingshots. Mobile phone service was blocked, and Internet links were also cut or slowed down.

Rioters on Sunday overturned barricades, attacking vehicles and houses, and clashed violently with police in Urumqi, according to media and witness accounts. State television aired footage showing protesters attacking and kicking people on the ground. Other people, who appeared to be Han Chinese, sat with blood pouring down their faces.

There was little immediate explanation for how so many people died.

The government accused a Uighur businesswoman living in the U.S. of inciting the riots through phone calls and "propaganda" spread on Web sites. Exile groups said the violence started only after police began violently cracking down on a peaceful protest complaining about a fight between Uighur and Han factory workers in another part of China.