Whenever there are urgent reasons for the filling of a vacancy in any position, and there are no names on the eligible list for such appointment, the appointing officer or body may nominate to the commission for noncompetitive examination, and if such nominees shall be certified by the commission as qualified after such noncompetitive examination, he may be appointed provisionally to fill such vacancy until a selection and appointment can be made, after competitive examination, in the manner prescribed in this act. No such provisional appointment shall continue for a period longer than three months, nor shall a successive provisional appointment be made to the same position. It shall thereafter be the duty of the commission to hold a competitive examination and certify the names of a list of eligibles and a regular appointment shall then be made from the names or name submitted by the commission: Provided, however, That nothing herein contained shall prevent the temporary appointment without examination of persons as fire apparatus operators in emergency cases.