Mobs of Han Chinese wielding meat cleavers and clubs and groups of Muslim Uighur men beat people in the streets of the capital of China's Xinjiang region Tuesday. The government imposed a curfew as it tried to stem communal violence after a riot that killed at least 156 people.

Members of the Muslim Uighur ethnic group attacked people near the Urumqi's railway station, and women in headscarves protested the arrests of husbands and sons in another part of the city. Meanwhile, for much of the afternoon, a mob of 1,000 mostly young Han Chinese holding clubs and chanting "Defend the Country" tore through streets trying to get to a Uighur neighborhood until they were repulsed by police firing tear gas.

Panic and anger bubbled up amid the suspicion in Urumqi. In some neighborhoods, Han Chinese — China's majority ethnic group — armed themselves with pieces of lumber and shovels to defend themselves. People bought up bottled water out of fear, as one resident said, that "the Uighurs might poison the water."

The outbursts happened despite swarms of paramilitary and riot police enforcing a dragnet that state media said led to the arrest more than 1,400 participants in Sunday's riot, the worst ethnic violence in the often tense region in decades.

Trying to control the message, the government has slowed mobile phone and Internet services, blocked Twitter — whose servers are overseas — and censored Chinese social networking and news sites and accused Uighurs living in exile of inciting Sunday's riot. State media coverage, however, carried graphic footage and pictures of the unrest —showing mainly Han Chinese victims and stoking the anger.

The violence is a further embarrassment for a Chinese leadership preparing for the 60th anniversary of communist rule in October and calling for the creation of a "harmonious society" to celebrate. Years of rapid development have failed to smooth over the ethnic fault lines in Xinjiang, where the Uighurs (pronounced WEE-gers) have watched growing numbers of Han Chinese move in.

Wang Lequan, Xinjiang's Communist Party secretary, declared a curfew in all but name, imposing traffic restrictions and ordering people off the streets from 9 p.m. to 8 a.m. Wednesday "to avoid further chaos."

"It is needed for the overall situation. I hope people pay great attention and act immediately," he said in an announcement broadcast on Xinjiang television.

Foreign Ministry spokesman Qin Gang blamed the violence on Rebiya Kadeer, the U.S.-exiled Uighur leader.

"Using violence, making rumors, and distorting facts are what cowards do because they are afraid to see social stability and ethnic solidarity in Xinjiang," he told a regular news conference.

Qin said Kadeer was behind the violence, adding "she has committed crimes that jeopardize national security." Evidence had been found against her, Qin said, but refused to give details.

Sunday's riot started as a peaceful demonstration by Uighurs over a deadly fight at a factory in eastern China between Han Chinese and Uighur workers. It then spiraled out of control, as mainly Uighur groups beat people and set fire to vehicles and shops belonging to Han Chinese.

After retreating from the tear gas, some among the Han Chinese mob were met by Urumqi's Communist Party leader Li Zhi, who climbed atop a police vehicle and started chanting with the crowd. Li pumped his fists, beat his chest, and urged the crowd to strike down Kadeer, the 62-year-old Uighur leader.

"Those Muslims killed so many of our people. We just can't let that happen," said one man in the crowd, surnamed Liu. He carried a long wooden stick and said the Han Chinese were forced to take up arms. People walked by with bloodshot eyes from the tear gas.

To the east, on Xingfu road, Han Chinese residents stoned a car with two Uighurs inside until it crashed, pulling one passenger out and beating him until police arrived, residents said.

Elsewhere in the city Tuesday, about 200 people, mostly women in traditional headscarves, took to the streets in another neighborhood, wailing for the release of their sons and husbands in the crackdown and confronting lines of paramilitary police. The women said police came through their neighborhood Monday night and strip-searched men to check for cuts and other signs of fighting before hauling them away.

"My husband was detained at gunpoint. They were hitting people, they were stripping people naked. My husband was scared so he locked the door, but the police broke down the door and took him away," said a woman, who gave her name as Aynir. She said about 300 people were arrested in the market in the southern section of town.

The protesters briefly scuffled with paramilitary police, who pushed them back with long sticks before both sides retreated.

Foreign reporters on a government-run tour of the riot's aftermath witnessed the protest and without their presence, the incident might have gone unreported given the media controls.

Groups of 10 or so Uighur men with bricks and knives attacked Han Chinese passers-by and shop-owners midday outside the city's southern railway station, until police ran them off, witnesses said.

"They were using everything for weapons, like bricks, sticks and cleavers," said a Mr. Ma, an employee at the Dicos fast-food restaurant nearby. "Whenever the rioters saw someone on the street, they would ask 'are you a Uighur?' If they kept silent or couldn't answer in the Uighur language, they would get beaten or killed."

It was not immediately clear if anyone was killed in those reported attacks.

Li, the Communist Party official, told a news conference that more than 1,000 people had been detained as of early Tuesday and suggested more arrests were under way. "The number is changing all the time. We will let those who did not commit serious crimes go back to their work units."

The official Xinhua News Agency said earlier Tuesday that 1,434 suspects had been arrested, and that checkpoints had been set up to stop rioters from escaping.

Officials at the news conference said they could not give a breakdown of how many of the dead were Uighurs and how many were Han Chinese.

Sunday's riot started as a peaceful demonstration by 1,000 to 3,000 people protesting the June 25 deaths of Uighur factory workers killed in a brawl in the southern Chinese city of Shaoguan. Xinhua said two died. Messages circulating on Internet sites popular with Uighurs put the figure higher, raising tensions in Xinjiang.

In a sign the government was trying to address communal grievances, Xinhua announced Tuesday that 13 people had been arrested over the factory fight, including three from Xinjiang. Two others were arrested for spreading rumors on the Internet that Xinjiang employees had raped two female workers, the report said, citing a local police deputy director.

The disturbances in Xinjiang carry reminders of the widespread anti-Chinese protests that shook Tibet last year and have left large parts of western China living with police checkpoints and tightened security. Like the Tibetans, Uighur unrest has not been muted by rapid economic development, though the government publicly is unwilling to address ethnic tensions.