Back to the Dungeon
When our heroes appoach the cave again, they notice the thin wisps of smoke drifting up from several holes, what seems to be a natural sort of chimney, in the top of the cave. There are three guards visible, stationed on top of the cave in some kind of hastily constructed fortification of stone and wood. [They currently have 60% cover, and it stands to reason that this could be easily increased with a moment's movement, or 'hunkering' if you prefer.] It would stand to reason that there are still orcs stationed below in the cave itself, as well. None are yet visible down below from your present vantage point.
[The Heroes are all at full HP and capabilities, if anyone has forgotten to rejuvenate a PC.]