In the aftermath of violence on Sunday that left 156 people dead and more than 1,000 injured according to official figures, Uighur and Han mobs roamed the streets of Urumqi armed with cleavers, clubs, and sticks, beating up passers-by, according to reports from the city.
Some 20,000 security forces blanketed Urumqi Tuesday, using tear gas to disperse rival crowds and prevent further bloodshed, as up to 1,000 young Han men sought out Uighurs and looted their property. It was unclear whether anyone had died in the assaults. (Getting Uighurs to talk was impossible, and even Chinese scholars have been unwilling to speak with foreign reporters about the situation.)
"It is needed for the overall situation," he said in a televised announcement. "I hope people pay great attention and act immediately."
In one incident, riot police used baton charges and tear gas to keep enraged, rock-throwing crowds of Uighurs and Han Chinese apart. Hundreds of other policemen spent the afternoon preventing a mob from reaching a predominantly Uighur quarter of the city.
Why Uighurs resent Han Chinese
The violence has underscored the depth of intercommunal resentments in the far western province of Xinjiang, where the indigenous Uighur people say Han Chinese take the best jobs and the most powerful political positions while treating them as second-class citizens.
Many of the Han demonstrators Tuesday said they were seeking revenge for the victims of Sunday's mayhem, which broke out when a peaceful demonstration by Uighurs turned violent.
The authorities have not said how many of those victims were Han, how many were Uighur, and how many were policemen. An official at one hospital that treated 291 injured people told reporters that 233 of them were Han.
Government television broadcasts have aired pictures of the wounded, concentrating on Han casualties, but on Tuesday night carried no news of any revenge attacks on Uighurs.
Officials cut Internet to quench riot
The government has housed foreign journalists in the only hotel in Urumqi that still has an Internet connection, but has cut off most of the rest of the city from contact with the outside world. Mobile phone connections from Xinjiang are patchy, and Twitter and YouTube have been blocked in China.
"We cut Internet connections in some areas of Urumqi in order to quench the riot quickly and prevent violence from spreading to other places," Urumqi Communist Party Secretary Li Zhi told the official Xinhua news agency.
The Chinese government has accused exiled Uighurs, especially World Uyghur Congress leader Rabiya Kadeer, of masterminding and organizing Sunday's violence through e-mails. Ms. Kadeer has strenuously denied the charge.
Meanwhile events in Urumqi echoed elsewhere in the world, as Uighur protesters threw stones at the Chinese embassy in The Hague, and tried to torch the Chinese consulate in Munich.
The top United Nations human rights official, Navi Pillay, called on the Chinese government and ethnic groups in Xinjiang to refrain from further violence, and urged the authorities to treat detainees humanely.
Urumqi police have arrested 1,434 suspects since Sunday, according to Xinhua, which quoted Mr. Li as saying that more arrests are expected.