I am probably the only one here who thinks it is quite possible that no Pakistani or Muslim or Uighur had anything to do with these attacks at all.
Instead, the Chinese government is making a statement signaling a sea-change in its Pakistan policy. How can that be, you may ask?
Consider that after the Abbotabad incident on May 2nd the Pakistani press and government lauded China for its full support of Pakistan. That was a misrepresentation - a deliberate one - of Chinese policy.
link That couldn't have pleased the Chinese. So how were the Chinese to respond?
In my opinion, the Chinese conception of language and communication is not quite like our own. The letters on this page form words that combine into things and actions. In English cause and effect are logically ordered to describe something accurately, which is one reason why English is so useful in everything from science research to waging battles.
Chinese and Japanese writing, by contrast, is a collection of ideographs. Cause and effect are not so important as the final picture desired. This allows unusual flexibility in reaching desired ends, albeit at the cost of poor interpersonal communication. (Churchill, for example, theorized that the Japanese lost battles because their language wasn't flexible enough for widely-spaced commanders to communicate quickly when situational changes occurred that were not according to plan.)
So the Chinese, while displeased with Pakistan, are not going to limit themselves to direct contradiction, as an American would. After all, that would set up a confrontation and counter-accusations by Pakistan. Why set up China for criticism at all if another way is available?
So the Chinese may have bombed places in Xinjiang themselves with the idea of blaming Pakistan afterward. The desired effect is achieved: Pakistan and Pakistanis are put on notice that Pakistan does not have unquestioned and full Chinese support. Pakistani government officials can't deny Chinese accusations without damaging the relationship they publicly prized so highly - both Pakistani-Chinese relations and their own personal credibility and prestige would be damaged.
Note that China gains justification for intervention in Pakistan in the future - filling the void when the Americans leave, perhaps.
Chinese officials can do such dastardly deeds - even killing their own citizens within China itself - simply because they work for a police state, not a democracy. The FBI and CIA could never do such a thing, and it's a stretch for a Westerner like me to even think of it - only prolonged contact with Chinese and historical study suggest the possibility and, to China's leaders, the desirability of such a course of action.