The Essex County Prosecutor's office confirmed that the incident started around 4:45 p.m. Monday when the 16-year-old tried to rob the officer.
The officer fired, hitting the boy in the chest.
Authorities say the suspect dropped his gun and fled, but turned up later in East Orange General Hospital, where he died late Monday.
Police have not released the name of the suspect or the officer.
An off-duty Essex County sheriff's officer shot at a suspect in a car theft attempt in Newark on Sunday. No one was injured in that incident.