Global Times says that Xinjiang is under control. China Daily says that rumours are damaging Xinjiang. This may have something to do with rumours that four people have been killed and 13 injured in renewed ethnic rioting in Korla. All the victims are supposed to be Han and two are supposed to have been beheaded.
This harks back to the violence in 2009, but it's also worth remembering that you can say anything negative about Uighurs in the Sinosphere and count on being believed.The slightly bizarre reference to cake in the China Daily story refers to a popular belief that gangs of Uighur traders get together and force hapless Chinese victims to buy cake at exorbitant prices.
Given stuff like this it's too early to confirm anything about what might have happened in Korla. But it's interesting that the Uighur government are pushing hard on the anti-rumour and 'everything under control' fronts. Additionally, Uighur sources are reporting a lockdown on flights in and out of the province.
Update: an attack of some sort has been confirmed by local police. No more details yet.