That seems to be an abuse of the security check feature by Facebook's part. 6 mile radius for a fire in a ridiculously large city? As mentioned in other comment

That seems to be an abuse of the security check feature by Facebook's part. 6 mile radius for a fire in a ridiculously large city? As mentioned in other comments, that feature can be very useful in cases of natural disasters or large terror attacks that prompted the creation of this feature. (Although, to be frank, living in Istanbul, it had become somewhat annoying to mark myself safe every couple of weeks or so - though this is more directed towards the Turkish government than Facebook)