Therefore, they will attack anything in range, including all Black Mesa employees as well as Xen creatures. The Ceiling Turrets do not distinguish friends from foes.If not, the Turret can be disabled with explosives or gunfire.
When a switch is available, the player can always use it. Some are activated or deactivated by a switch, some deploy automatically. Ceiling Turrets are seen in several places within the Black Mesa Research Facility, concealed within the ceiling in an armored cupola.