what was that?

Hey, there was a muffled explosion sound tonight and our RV shook. Don looked at me and said, "What was that?" I opened the door and went outside, just like everyone else was doing. I heard all sorts of speculations: sonic boom, industrial explosion, refinery explosion (none close that I know of), earth quake, bomb. I didn't hear anyone suggest UFO, though. Nothing on the news yet. Oh well... life in the desert.