Further to mine, and to the Museum Security List piece that followed it,
the10am CET BBC news carried a report that two loud explosions were heard
in the building shortly before the fire was spotted.

Has anyone else heard this?  Possible the "explosions" were what UK fire
engineers call "flash-overs", i.e. the explosive ignition of
unburned infammable gases and other combusion products produced by the
smouldering or less violent burning, typically of wood or plastics.
However, there have certainly been terrorist fire bombings in Paris over
the years.

Patrick Boylan