The use of force to prevent the escape of an arrested person from custody is justifiable when the force could have been employed to effect the arrest under which the person is in custody, except that a guard employed by a correctional facility or a peace officer is justified in using any force, including deadly force, that he reasonably believes to be immediately necessary to prevent the escape of a person from the correctional facility.
Official text of the Texas Penal Code as published by the Texas Legislative Council.