It wasn't immediately clear what sparked the shootings, which occurred around 3:45 p.m. on Schuyler Terrace. Authorities would not disclose the victims' name or provide further details on the incident, including what type of weapon was used.
Acting Essex County Prosecutor Carolyn Murray said all three victims were taken to University Hospital in Newark. The man was pronounced dead there a short time later, while the other two victims - a man and a woman - were being treated for undisclosed injuries.
The county's homicide task force will lead the investigation.