You keep saying nothing happened, when even the screenshot says a lot, so how can i listen to you?
I regret not taking a picture where the whole area was filled with these monsters, so it was not 50 it was 5000 maybe. And forget these monster, but the fact that someone did it means that the same people who spawned these mobs could have spawned items easily.
I know you know more than me, but you are just being defensive and giving us any answers to what actually happened..