A gunshot and the subsequent police lights and sirens drew curious neighbors to the streets of their quiet Brooklyn neighborhood on Monday night. As they emerged from their homes, they saw a dead dog on the pavement, covered by a white sheet.

The dog’s owner was standing nearby, as was the off-duty Secret Service agent who had shot the animal. The agent told police officers that the dog had charged at him, he had reached for his firearm and he had fired once, striking the animal and killing it.

Even as details of the confrontation remained unclear on Tuesday, neighbors and others were stunned and appalled that a chance street encounter with a pet would end in its death.

“I can’t think of any dog that is so menacing that I feel I would need to have a firearm to protect myself,” said Walker Blankinship, who manages a stable near the site of the shooting.