Tex. Code Crim. Proc. art. 8.01

When any officer authorized to execute process is resisted, or when he has sufficient reason to believe that he will meet with resistance in executing the same, he may command as many of the citizens of his county as he may think proper; and the sheriff may call any military company in the county to aid him in overcoming the resistance, and if necessary, in seizing and arresting the persons engaged in such resistance.