An entire town was destroyed.

Fifteen or more dead and they are still counting.

I just reviewed the photos at Slate:

http://www.slate.com/articles/news_and_politics/photography/2013/04/west_texas_factory_explosion_and_memorial_photos.html

NH3 (anhydrous ammonia) is highly explosive.  It has a exothermic reaction with water.  Exothermic means it goes boom.  It is stored under pressure in liquid form and gas can leak.  The gas causes burns and will damage lungs which will kill you.  I was a volunteer fireman for 6 years in a small department in North West Florida.  We were trained for this because there was a fertilizer plant in the next county.  NH3 was shipped through our district.  We had a foam truck that was outfitted with brass tools.  Brass tools don't cause sparks.  We also knew when to evacuate everybody including ourselves.  NH3 in a pressure tank will cook off under certain conditions.   We had our share of tank truck accidents.   I read last year during the Texas drought that most of the fire departments that was fighting all the fires were volunteer units.  The state of Texas had cut back so much in funds for these departments that they didn't have the equipment or the training needed for their communities.  Many of the volunteers had to buy their own safety equipment. They bought old used fire trucks or converted old military 2 1/2 ton trucks into woods trucks.  Texas has more problems then dumb untrained and under equipped fire fighters, the state itself needs too take a good look at their lack of oversight and investment.  Why wasn't that tank farm moved away from a residential area.  You figure out how big of a explosion the chemicals make or how big a gas cloud can be released and then you know how long to make the drive way to the plant.  West Fertilizer should have been out in the north forty with the cattle.