Considering West's proximity to Waco, and the fact that twenty years ago tomorrow was the end of the
Waco Siege, and the fact that the Boston marathon bombings occurred just days ago, I really want to believe this was more than a simple accident. But for now I'm going to assume it just caught fire and exploded. Fertilizer can be very
inflammable.
If it was arson however, I believe there's a supervillain looking to blow up the US.