Maryland Code, Public Safety § 7-101

(1) a governmental subdivision, by its appropriate designated authority;

(2) a board or fire commission of a fire department or governmental subdivision;

(3) a fire department;

(4) a fire company;

(5) a rescue squad; or

(6) an emergency medical services unit, including an entity that provides emergency medical services at any level.

(c)(1) “Mutual aid agreement” means an agreement to establish and carry out a plan to assist in extinguishing fires and preserving life and property by providing fire fighting, rescue, or emergency medical equipment, personnel, and services.

(2) “Mutual aid agreement” includes a reciprocal agreement entered into in accordance with this section and § 7-103 of this subtitle before July 1, 1989.