An off-duty NYPD officer, responding to a Craigslist ad about a car for sale, shot and killed one of the two men posing as sellers late Monday night in Springfield Gardens, Queens — after the pair tried to rob the officer at gunpoint, police said. Police are now searching for the second man, who they said fled in a white BMW.

The shooting on 145th Avenue near 177th Place was reported in a 911 call at 10:36 p.m., the NYPD said.

The suspect shot and killed by the officer was pronounced dead at Jamaica Hospital Medical Center at 11:14 p.m. Police have not released his identity. A black CO2-powered PT85 Blowback air pistol, which fires pellets but, according to the manufacturer’s website, is designed to act like and resemble a bullet-firing semi-automatic handgun, was recovered at the scene, the NYPD said.

The officer was taken to Long Island Jewish Medical Center in New Hyde Park for treatment of tinnitus. He was otherwise not injured, police said.

It was not immediately clear where the off-duty officer was from or to which precinct he is assigned.

Police said the off-duty officer had gone to Springfield Gardens in response to an ad on Craigslist offering a car for sale, believed to be the same white BMW used as the getaway car. Police said that after being met by the two men one of the suspects pointed a gun, now believed to be the air pistol, at the off-duty officer, who then fired at least one shot, killing the one suspect.

It was not clear if more than one shot was fired or if the second suspect was struck by gunfire or had been wounded.

Police said the investigation is continuing and that the second suspect remained at-large Tuesday morning.