Tex. Civ. Prac. & Rem. Code § 79.004

Except in a case of reckless conduct or intentional, wilful, or wanton misconduct, a person who is immune from civil liability for an act or omission that occurs in giving care, assistance, or advice with respect to the management of an incident to which this chapter applies is immune from civil liability for an act or omission that occurs during the execution of a training exercise intended to prepare the person to give that care, assistance, or advice.