What kind of explosion starts like this? It does not propagate from a source point and go outward, it is like an invisible gas cloud was suddenly ignited but keeps glowing for such a long time. I have never seen anything like it.
Speculation:
Was the underground structure filled with a highly explosive gas and then ignited?
Was the RV parked where a hole could be drilled and gas pumped down? (manhole covers in the street in that area seem to be positioned only in driveways where parking would not be allowed).