Reinforcements

After psi-emitter went down, prof. Sakharov - scientist from the nearby ecologist bunker - called in two Hinds to clean the surface part of Yantar facility from the remaining zombified stalkers.
However since stalker-ing is illegal, the pilots aren't really going to make difference if you'll happen to be in the target area. But they will not target you personally, and Sakharov warns you to steer clear of the facility.