Since the release of the Tac-Ops DLC and the accompanying vehicle physics update (which I presume might be the cause of this bug) my tank and/or crew can get killed by firing into a vehicle and blowing it up causing either the death of my crew or the explosion of my vehicle.
[[ https://www.reddit.com/r/arma/comments/7h4g86/shooting_close_killing_own_crew/ | Reddit ]]link (just in case)