16 Pa. Stat. § 4515
Whenever there are urgent reasons for the filling of a vacancy in any position in the police force or as fireman or fire inspector and there are no names on the eligible list for such appointment, the board of county commissioners may nominate a person to the commission for a noncompetitive examination, and if such nominee shall be certified by the commission as qualified, after such noncompetitive examination, he may be appointed provisionally to fill such vacancy until an examination for such position can be held. It shall thereupon become the duty of the commission, within three weeks from the date of provisional appointment, to hold a competitive examination for such position, and certify a list of eligibles to the board of county commissioners, and they shall then make a regular appointment as prescribed in this article. Nothing herein contained shall prevent the appointment without examination of persons temporarily as police officers, in emergency cases, for the suppression of riots, tumults, in times of war, pestilence, conflagration or public celebration.
16 P.S. § 4515