; (2) at the discretion of the Fire Chief, an officer or employee of the District of Columbia Fire and Emergency Medical Services Department who resides in the District of Columbia and is on call 24 hours a day; (3) at the discretion of the Director of the Department of Corrections, an officer or employee of the District of Columbia Department of Corrections who resides in the District of Columbia and is on call 24 hours a day; (4) at the discretion of the Chief Medical Examiner, an officer or employee of the Office of the Chief Medical Examiner who resides in the District of Columbia and is on call 24 hours a day; (5) at the discretion of the Director of the Homeland Security and Emergency Management Agency, an officer or employee of the Homeland Security and Emergency Management Agency who resides in the District of Columbia and is on call 24 hours a day; (6) the Mayor of the District of Columbia