This Refinery does not produce gasoline they primarily do jet fuel (big airfore customer) if you google their address 7811 South Presa San Antonio TX you will see this is right by Brooks AFB.
another thread here:
http://www.freerepublic.com/focus/f-news/2507276/posts
Third sentence in the above article:
"Refinery marketing director Jeff Morrow says the truck exploded late Wednesday morning at the facility that refines gas and jet fuel, but he had no other details".