UNION TOWNSHIP - Authorities say an off-duty New Jersey police officer fatally shot a man outside of a bar following an altercation.

Acting Union County Prosecutor Grace Park said that the Newark police officer shot 37-year-old Michael Gaffney with his service weapon. The shooting happened following an altercation at Paddy’s Place, a bar on the 900 block of Rosemont Avenue in Union Township, early Friday morning.

Gaffney, of Piscataway, was pronounced dead at the scene. 

The officer was taken to a local hospital for treatment of injuries that are not considered life-threatening. His name wasn't immediately released. He is an 11-year veteran of the Newark Police Department.

Officials did not say what led to the altercation.

Investigators say they are following state guidelines governing investigations involving use of deadly force by law enforcement.

The Associated Press wire services contributed to this report.