Executive Assistant Essex County Prosecutor Charlotte Smith says Veneziano told investigators he got out of his vehicle and identified himself as a police officer.
The 26-year-old was shot multiple times in the torso and neck by a lone suspect. Veneziano, who was not in uniform and not wearing a bulletproof vest, fired 13 rounds from his service weapon. It's not known if he hit the suspect.
Police are looking for a dark-colored Dodge that's possibly a Magnum, Nitro or Caliber.
The officer remains at University Hospital in Newark.
Information from: The Star-Ledger, www.nj.com/starledger