Police have seized 15 people for stabbing members of the public with hypodermic syringe needles in Urumqi, capital of northwest China's Xinjiang Uygur Autonomous Region, a senior local official said Wednesday.

Of the 15, four were officially arrested and prosecuted, said Zhu Hailun, head of the political and legal affairs commission of the Communist Party of China (CPC) committee in Xinjiang.

The court would pronounce judgment on the four in the near future, Zhu said.

Members of nine ethnic groups including Han Chinese, Uygur, Hui, Kazak and Mongolian had reported stabbing incidents to the police, said Zhu.

Police investigations are under way.

Yin Yulin, deputy director of the region's health department, said nobody had been infected or poisoned from being stabbed so far.

Health authorities have registered those who came to hospital after being stabbed and will carry out follow-up examination on them regularly, Yin said.

"The criminals' despicable acts have caused strong indignation from all ethnic groups in Xinjiang," Zhu said, adding the CPC Xinjiang committee and the regional government has ordered all-out efforts to crack the case and timely medical treatment for the victims.

A total of 197 people were killed and 1,600 injured in the July 5 riot in Urumqi.

(Xinhua News Agency September 3, 2009)