An off-duty NYPD cop shot a gunman who fired at him first during what appeared to be an attempted carjacking early Wednesday, authorities said.

The undercover cop had just left work and gotten into his car at the corner of East 87th Street and Foster Avenue in Canarsie around 2 a.m. when a 28-year-old man tapped on the driver’s window with a gun, NYPD Chief of Detectives Rodney Harrison said at a morning press conference.

The officer pulled over and got out of the car — at which point the gunman fired once in his direction, but did not strike him, according to Harrison.

“Our member of the service then pulled out his firearm, shooting several times at our perpetrator, striking him in the chest,” Harrison said.

He was also hit in the arm, authorities said.

The unidentified suspect was taken to Brookdale University Hospital Center with life-threatening injuries, according to Harrison.

The officer was not shot during the incident, but was taken to Mount Sinai Beth Israel for tinnitus, authorities said.

At this point, authorities do not believe the officer was followed or targeted, according to Harrison.

It also didn’t immediately appear that it was obvious to the suspect that the driver was a police officer.

The alleged carjacker had been carrying two guns and a knife, cops said.

One of those guns was wrapped in a rubber glove and shoved in his butt, according to sources.  Photos from the scene show a gun wrapped in a bloody glove.

He has a lengthy criminal history, with at least seven unsealed arrests dating back to 2011, according to police. The most recent bust was for vehicular manslaughter in April 2019, authorities said.

Additional reporting by Craig McCarthy