URUMAQI; The police used tear gas and public appeals today to break up crowds marching on government and Communist Party offices in western China to protest a lack of public security after a bizarre series of syringe stabbings that appeared ethnically motivated.

Thousands of people, mostly from the Han Chinese majority, took to the streets of the city of Urumqi for a second day to demand increased security in the Xinjiang regional capital, still jittery after riots two months ago left nearly 200 people dead.

The protesters want punishment for those behind the July riots between Han Chinese and Muslim Uighurs, and for the culprits in the stabbings with syringes or needles in the past two weeks that state media has said targeted predominantly Han Chinese victims.

Hundreds of young Han Chinese men protested outside the headquarters of Xinjiang party secretary Wang Lequan - an ally of President Hu Jintao- chanting for him to step down.

Armed police in riot gear marched into the crowd to push people back. After several surges, the police broke up the demonstrators, some of whom were singing the national anthem. The smell of tear gas drifted over parts of the city. The official Xinhua News Agency also said tear gas had been used.

The security forces did not appear to be using excess force, but armed police seized video and cameras from cameramen and photographers from The Associated Press covering the protest. The protests have thrown the city of 2.5 million into confusion, with vehicles banned from streets and almost all shops and schools closed. Wang spoke to protesters Thursday to call for restraint. Hong Kong Cable TV reported that paramilitary police had fired tear gas to disperse a crowd of about 1,000 near the city government offices Friday morning. One Han man, who brought his 9-year-old daughter because her school was closed, was seen arguing with paramilitary police.

“It’s been two months already. How many more months are we going to wait, how long before us Han can feel safe?” said the man, who would give only his surname, Ma.

A truck with loudspeakers circled behind him, with a recorded voice saying repeatedly: “Disperse. Don’t stay here. Think of the nation.” Hong Kong Cable and and another broadcaster, RTHK, both reported that two cameramen and a reporter from Hong Kong were detained while covering a protest. Hong Kong Cable said the three were forced to kneel, with their hands being tied, before they were taken away.

There was no immediate independent confirmation of the reports. RTHK also said about 5,000 Han Chinese carrying national flags protested peacefully on Renmin Road, demanding that Wang step down.

The report said paramilitary police fired several tear gas rounds to disperse them.

One middle-aged Han Chinese said police should leave the protesters alone.

“They should be catching the terrorists, not harassing the people,” said Ji Xiaolong. “I have to wonder if Hu Jintao really knows what is going on here.” All access to Uighur areas of the city had been cut off, with security forces forming barriers at street entrances.