I havent unlocked the fence yet. I shot a bit haphazardly in frustration at the box but I never noticed a lock. I will try to reload a save and try it again. If there is a lock, I just shoot it and should be able to loot then? I had another wagon I grabbed in frustration and it had 2 crate looking things in the back that I could not look but it didnt look like they had locks but also showed up with eagle eye.