(a) The use of deadly force is authorized only under exigent circumstances where the Protective Force Officer reasonably believes that such force is necessary to:

(1) Protect himself from an imminent threat of death or from serious bodily harm;

(2) Protect any person or persons in or upon the SPR from an imminent threat of death or serious bodily harm.

(b) If circumstances require the use of a firearm by a Protective Force Officer, the Officer shall give a verbal warning (e.g., an order to halt), if feasible. A Protective Force Officer shall not fire warning shots under any circumstances.