Nine suspects believed to be responsible for syringe attacks in the Xinjiang Uygur autonomous region communities of Hotan, Altay and Kashgar are in custody.
The arrests follow reports of syringe attacks in several cities in the autonomous region after a spate of similar attacks in the region's capital, Urumqi, that led to massive protests.
Six of the suspects were caught in Hotan, according to the Hotan public security bureau on the local government's website on Wednesday.
Of the six, two have already been officially detained.
By Sunday, nine syringe attacks had been reported in Hotan, but only three had been confirmed, the bureau said.
Among the three hospitalized victims, two were Han Chinese and the other was Uygur.
So far, none of the victims is believed to have contracted a disease or been exposed to poisoning.
Police are offering a 5,000 yuan ($735) reward for information about the attacks, Hotan police said.
An official from the public security bureau of Altay region confirmed on Tuesday that two syringe attack suspects were in custody there.
"Five possible syringe attacks were reported to the public security bureau by Tuesday, four of which were false alarms. The other case is genuine. The victim did not show any abnormal symptoms," said Ahlebeck, deputy director of the public security bureau of Altay region.
Ahlebeck said police apprehended a 35-year-old and a 21-year-old in connection with the attack. Further investigation is under way.
A syringe attack suspect was caught on Monday in Kashgar, according to Wang Jianhua, spokesperson for the local government.