SuperSalad,
Carus also makes Polymers. Given that, they may have reducers on site too. Mixing oxidizers and reducers in concentrated form is kind of like mixing matter and anti-matter. BOOM! Flash Fire! This is my pure speculation. I have read nothing that suggests that is what happened. I am interested in hearing the real reason. Hopefully we don't have to wait months/years on the CSB!
Good Luck,
Latexman