Amid concerns for terrorism during the Olympics, the cause of this explosion is as yet uncertain.
A woman on the bus is quoted as having said, "“车门刚刚打开,突然就闻到一股怪味,然后车厢当中一个座位烧起来了。”" [ Editor's translation: The door of the bus had just opened and suddenly I smelled a strange odor, and then a seat in the center of the bus burst into flame.]
Spontaneous combustion of a passenger or something more sinister? A trial run?