At least 140people were killed as riots erupted in northwest China, where protesters from the ethnic Muslim Uighur community went on a rampage, prompting a statewide crackdown.
The violence in Urumqi, the capital of Xinjiang state, has left 140 people dead and injured 820 others, state-owned Xinhua news agency reported on Monday, quoting the regional public security department.
Police cracked down on protesters on Sunday night, arresting several hundred of them, "including more than ten key figures who fanned the unrest on Sunday," the official said. Xinhua said the police was still searching for about 90 other key figures in the city.
"While 57 people were confirmed dead at the scene of the clash, others succumbed to their injuries at a hospital," a spokesman of the regional government told newsmen.
The latest riots are the worst to have hit the region that is marked by a history of unrest and separatist movements.
Hundreds of protesters, who hit the streets on Sunday, were demanding an investigation into a clash between Uygur and Han Chinese labourers at a toy factory in southern China in June, in which two people were killed.
The violence erupted after an initially peaceful demonstration went out of control with violent protesters smashing vehicles and clashing with the police. Uygur exile groups alleged that the violence started only after the police launched a violent crackdown.
Riots had erupted in the region ahead of the Olympics held last August. Seventeen policemen were killed in Kashgar on August 4 in what China described as a 'terrorist' attack.
Xinjiang has roughly eight million Uighurs, who have accused the government of suppressing their rights.