From The Wall Street Journal:

For the latest evidence that China is neither as stable nor as harmonious as Beijing would have you believe, turn to the restive Xinjiang province in the west. During the evening rush hour on April 30, two men stabbed passersby outside the Urumqi South train station and then set off explosives, killing themselves and one other person and injuring 79. The incident was especially shocking because it happened on the same day President Xi Jinping was visiting the city.