Destroyed pre-placed buildings damage everything around them continuously on populated servers. All our attempts to repro the problem failed but it works almost each time on highly populated servers. Only evidence is collected.
Video evidence 1:
(72 players, ArmA 3): http://www.youtube.com/watch?v=yQLg5RYlXgU
We destroyed lighthouse which also destroyed everything around it (I assume that damage was multiplied by number of players). Lighthouse keeps damaging everything around it even after being destroyed as observed at 1:20, we both die at the same time. Later off video it kept damaging everything around it again and again which continues until server gets restarted.
Video evidence 2:
(30 players, ArmA 2): http://www.youtube.com/watch?v=HrbLtMQy0gU
Destroyed building kept exploding generating lots of FX around it also damaging players and vehicles if you get close to it. Each "explosion" also spawned ruins underground by the number of players on the server.
Damage proportional to number of players:
Damage wave happens moment after new player finishes loading: