Article said that he self-identified as “Jiang” from Inner Mongolia. Most likely Han? If so, that really narrows things down (not, haha). Hui are only a very small minority there, so Muslim? Possibly, but you know that they’re in the doghouse (American figure of speech) and tend to be closely observed when deviating from routines.
There was smoke reported outside the embassy, and police referred to it as a firecracker. Looks like a simple black powder bomb, maybe.
I can’t speculate on it at all. It appears to be a desperate act of a crazy man. He was not a pro, unless we’re getting incorrect info from the local authorities there.