The Ministry of Public Security deployed 31 special police units from 31 cities across the country to Xinjiang Uygur autonomous region to ensure public order after the July 5 riots, Xinhuanet.com, the website of the Xinhua News Agency reported Monday.

The police units took 37 charted planes to Urumqi and arrived 11 hours after being ordered to the region.

Most of the police units were involved in the Wenchuan earthquake rescue. Some also dealt with the “March 14 riots” in Tibet, while still others assisted with security for the Beijing Olympics, Xinhua said.