Victory!
Your Templar squad has survived the onslaught at the bottom of the surface elevator.
The great elevator's doors have opened wide enough to allow your squad to pass through.
A security terminal on the far side has allowed you to shut the horde behind you.
Background
Your squad has discovered strange organic-metallic organisms harboring in the elevator landing deck.
Many moons and planets have a layer of near-surface rock which is softer and can be penetrated by ATAS scans. Below that surface rock is the deep-core layers, which cannot be scanned. You have descended beyond the range of the ATAS scanners.