They won't have to look too hard.

Judging by how those scorch marks are now cool to the touch, whatever happened wasn't too long ago, but it's definitely over by now. More than hours, less than a week.

Between the tracks in the sand, the visible battle damage scattered all over the place, and the open door cracked and hanging off its' hinges... there's only one way to go:

Down into the excavated compound.