Man shot after trying to rob undercover police officer in New York

Experts believe hundreds of non-uniform detectives are operating around the city

The scene was sealed off by police (GETTY IMAGES)

A man tried to rob an undercover detective at gun point in New York - only to be shot by the policeman.

The 20-year-old suspect approached the plain-clothed officer in the city's borough of Brooklyn as he was investigating another crime, and demanded his property.

He realised his mistake when a gun was drawn on him by the policeman, and he was shot once in the arm and once in the torso, according to New York Police Department (NYPD).

Police said the would-be robber had two accomplices, who were allegedly involved in a scam in which they lured prospective property tenants to nonexistent apartments.

Patrick Conry, chief of Brooklyn's detectives, said the three men would post fake rentals on Craigslist and then rob those who met them for a viewing.

The suspect was taken to Kings County Hospital after being shot, and was understood to be in a stable condition in custody.

Another 16-year-old suspect was also arrested, police said, while the third accomplice was being hunted.

A firearm was also recovered at the scene.

Plain-clothed policemen are a significant part of New York Police Department's operations in the city, it was reported in May this year.

Of the roughly 20,000 officer patrols, experts believe non-uniform detectives rank well into the hundreds.

Their role is to target "the small segment of the population that commits most of the crime in New York City", James O'Neill, chief of the department, said at the time.

No one else was injured in the incident on Sunday evening. Police said the investigation was ongoing and charges are pending.