Tex. Gov't Code § 418.006

An officer or employee of a state or local agency, or a volunteer acting at the direction of an officer or employee of a state or local agency, is considered for purposes of Section 437.222 to be a member of the Texas military forces ordered into active service of the state by proper authority and is considered to be discharging a duty in that capacity if the person is performing an activity related to sheltering or housing individuals in connection with the evacuation of an area stricken or threatened by disaster.