Question

Hello Rabbi,
At my workplace, a lot of people smoke and drink coffee in the emergency stairwell.
One day there was nobody there, and while I was hurrying I stepped on a coffee cup that shattered; it had been placed one step below me.
A few minutes later I saw the owner of the cup with a broom, but I just kept going as usual. Am I obligated to tell him that I was the one who caused the damage, or to pay him?
Because how can someone be expected to suspect that there would suddenly be a glass cup there if nobody is around? On the other hand, it is a place where people regularly drink coffee and smoke. But usually if they put a cup on the stairs, they stay near it…