On application of the chief executive officer or governing body of a county or municipality during an emergency, the governor may proclaim a state of emergency and designate the area involved. For the purposes of this section an emergency exists in the following situations:

1. (1) a riot or unlawful assembly by three or more persons acting together by use of force or violence;
2. (2) if a clear and present danger of the use of violence exists; or
3. (3) a natural or man-made disaster.

Acts 1987, 70th Leg., ch. 147, Sec. 1, eff. Sept. 1, 1987.