Point: an everyday citizen would be under an affirmative duty to retreat if he could do so in complete safety to himself. Police are NOT under such obligation. They,once on scene, are obligated to follow the incident through. NO retreat.
Citizens of the state of Texas have no duty to retreat.
PENAL CODE. TITLE 2. GENERAL PRINCIPLES OF CRIMINAL RESPONSIBILITY. ... There is no duty to retreat before using deadly force justified by Subsection (c) or (d).