Chinese authorities say religious extremists carried out an apparent suicide bombing on April 30 at a railway station in Urumqi that left three people dead and 79 wounded.
State media on May 1 said two of those killed were the attackers, who stabbed people with knives and then detonated explosives they were carrying.
China's state media call the attack a "violent terrorist attack" and said the two suspects has "long been involved in religious extremism."
Chinese President Xi Jinping, who was just finishing a visit to the Xinjiang Uyghur Autonomous Region when the attack occurred, demanded "decisive action" after the attack.
Dilxat Raxit, a spokesman for the exile group the World Uyghur Congress, claimed more than 100 Uyghurs had been detained since the April 30 attack.
Based on reporting by Reuters, AFP, and AP