Police were investigating after an off-duty US Secret Service agent shot and killed a dog in New York City, authorities said.

The shooting happened shortly after 9.30pm on Monday in the Windsor Terrace neighborhood of Brooklyn.

A New York police spokesman said the agent, whose name was not released, turned a corner and was charged by the dog. He said the agent fired one shot, killing the dog.

The Secret Service said in a statement that “an off-duty Secret Service employee was involved in the shooting of an unrestrained and aggressive canine” in Brooklyn.

A photo in the Daily News showed the dog’s paws and leash poking out from under a sheet on the sidewalk. A Secret Service spokesman said the dog was wearing a leash but no one was holding it when the animal charged the agent.

The Daily News reported that the dog was a female Belgian shepherd. The newspaper said one of the dog’s owners, whom it did not name, said: “She scared a cop who was walking home. He shot her and she’s dead.”

A witness told the New York Post the dog was “splayed out on the ground” after the shooting.

“And then I think the owner – man and a woman, it was a couple – they wanted to touch her and the police wouldn’t let her. I remember him going to the dog and the sheet,” the witness said.

Walter Blankinship, stable master at the Kensington Stables, across the street from the shooting scene, told the Daily News he heard the dog owner curse at the shooter, saying: “I can’t fucking believe you let the gun go off.”