N.J. Stat. Ann. § 40A:14-51

In cases of conflagration or other emergency, the officials in charge of the paid or part-paid fire department and force in any municipality, shall have authority to retain on duty any member and officer of such department and force during the period of the emergency, but in any such case and within 12 months thereafter, such member or officer shall be given a day off or proportion thereof for the extra time so served by him during the emergency.