N.J. Stat. Ann. § 40:11A-22.5

No parking enforcement officer may carry a firearm while engaged in the actual performance of the officer's official duties. A parking enforcement officer shall be deemed to be on duty only while the officer is performing the public safety functions enumerated in paragraph (d) of subsection (3) of section 22 of P.L.1948, c. 198 (C. 40:11A-22(3)(d)) on behalf of a parking authority and when that officer is receiving compensation, if any, from the parking authority at the rates or stipends as shall be established by ordinance.