Reports from China say at least 31 people were killed and 90 wounded by attackers who drove two vehicles into a crowded market and threw explosives out the windows.
The attack was in Urumqi, the capital of the restive Xinjiang region that is home mostly to Muslim Uyghurs.
In a statement, the Xinjiang regional government called the early morning May 22 attack "a serious violent terrorist incident of a particularly vile nature."
The resource-rich western region has seen increasing violence in recent months.
Beijing says it faces a terrorist threat from separatists there who are driven by Islamic extremism and support from foreign groups.
Critics say the security threat is exaggerated to justify hard-line measure, saying economic inequality and religious repression of Uyghurs is the cause of unrest.
Based on reporting by Reuters, AP, AFP, and Xinhua