Storm Over Warlock by Andre Norton [republicV]

The Throg task force struck the Terran survey camp a few minutes after dawn, without warning, and with a deadly precision which argued that the aliens had fully reconnoitered and prepared that attack. Eye-searing lances of energy lashed back and forth across the base with methodical accuracy. And a single cowering witness, flattened on a ledge in the heights above, knew that when the last of those yellow-red bolts fell, nothing human would be left alive down there. And so Shann Lantee, most menial of the Terrans attached to the camp on the planet Warlock, was left alone and weaponless in the strange, hostile world, the human prey of the aliens from space and the aliens on the ground alike.