More on the warehouse fires from calhypo.
From the Northeast Ohio Fire Prevention Association:
"As a Class 3 oxidizer, cal hypo is generally considered to be the most dangerous of the common pool sanitizing chemicals as its presence in several fires involving big box retailers such as Sam’s Club, Lowes, and Walmart, has resulted in fires so intense that they completely overcame the sprinkler systems and in several cases led to the total destruction of the facility."

http://www.neofpa.org/Pool%20Chemicals.pdf

I'm a calhypo user myself, and use caution with handling it.

Cheers