Possible explanations would be severe corrosion, vandalism, or some previous structural damage.
You forgot aliens from Mars, a man-portable surface to air missile, spontaneous human combustion, good Catholics that encountered the Rapture, the possibility that the sound barrier exists and someone finally hit it, an angry prehistoric bird, flatulence, swamp gas, the fact that it
was France, and of course tire spiders.
Ya gotta love speculation. Any more wild ideas?