A 28-year-old unarmed man has been killed after a rookie police officer shot him in New York's Brooklyn borough.
New York City Mayor Bill de Blasio said that the shooting late on Thursday in the darkened stairwell just before midnight was unprovoked.
The race of the victim and the shooter was not reported.
"We don't know enough yet, but it does appear to have been an accident," de Blasio at a press conference.
"This was a tragedy."
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
But he cautioned that the shooting was not like two other cases - those of Michael Brown, the unarmed black teenager shot in August by a white police officer in Ferguson, Missouri and a recent New York case where a black man died after police put a strangle hold on him.
"Each incident is different ... each of them has (its) own dynamic," de Blasio said.
"This is a tragic situation, that's the bottom line."
De Blasio noted, however, that relations between New York police and communities of colour were far from healed, and the city was working to "reform those dynamics".
Brooklyn district attorney Ken Thompson said the incident warranted an "immediate, fair and thorough investigation".
The police officer, who had been on the job for less than one and a half years, has been reassigned and stripped of his badge and gun.
According to the FBI, about 400 people are shot and killed by police every year across the United States.
