No idea how this happened
Saw this in a discord server, video belongs to Taco Man
Wooo, that’s brutal
The most dangerous thing was there, sewer 
It’s a known, rare bug. Fatshark have made several attempted fixes to it, which seem to have decreased its incidence (and it was always rare), but I guess it can still happen. Man, happening in FoW is extra-lame, though.