Almost as soon as the news hit about the explosion in West, Texas, reports agreed that anhydrous ammonia was involved, and I began hearing how dangerous it is to let water get near the stuff.
Here is a very brief CNN interview explaining that a plant of this sort generally is considered very safe, but apparently there was a small fire, then firehoses, then . . . .
Not using firehoses near the anhydrous ammonia tanks doesn't seem to have been part of the emergency plan for the plant or the town. There are reports that the EPA was unhappy with the place in 2006, but it was a minor problem about having an emergency plan on file that was quickly remedied to the EPA's satisfaction. OSHA hasn't been onsite since 1985.
The plant is nestled among homes, schools, and a nursing home, but it originally was out in the country. The very small town grew up around it in apparent ignorance of the danger. The head of the local EMS reports that he was conducting some kind of training at the nursing home the night of the explosion. Although he didn't explain exactly what he feared might happen, somehow he got the idea he'd better move the residents to the far side of the building, which he'd just about finished doing when the plant blew. Even so, the roof came down on them. He looked pretty beat up on camera, and couldn't account for most of his personnel.
I'm familiar with the 1947 Texas City blast, naturally, growing up in Houston, but was surprised to read about a worse one in Halifax, Canada, in
1917, which leveled two-and-a-half square kilometers. Two thousand people were killed, including many spectators who were lined up on the haborfront watching a fire in a munitions ship stuffed with TNT. The ship had been struck in harbor by a Belgian relief vessel.