MSNBC reports that knife wielding assailants kill 36 people in Xinjiang before being killed by authorities. I am sure someone will make a comment about how strict gun control did not prevent this incident, and another will make a comment about how nine policemen, who would presumably be armed with firearms, were killed and that them having firearms didn't protect them from knife wielding assailants, but that would miss the larger point. The point being is that this was not an attack by a lone crazed individual against civilians while, it was a an armed assault of a police station by multiple individuals. It wasn't a random act of violence, it was a planned attack.
Given that Xinjiang is a northwestern province bordering Afghanistan and Pakistan, and that, most importantly, the territory has a plurality of Muslim Ughyrs. It is pretty to easy to see why this event happened. This territory has alternatively been under, and independent of, the control of the Han for centuries. As terrible as the deaths of innocent people are, and they are terrible, the real issue is whether or not these sort of events are a signal of growing unrest in China's frontier regions. It is really hard to say, since both Tibet and Xinjiang have had periods of unrest recently, but this attack is new. There have been protests and riots, but those are rather directionless and often fizzle out or are suppressed quickly. An assault on a government building, the police no less, is much different. Time will tell if this is a one off instance, or the beginnings of something larger.