NEW YORK — New York City police officers shot and killed a black man who was known to be mentally ill on a Brooklyn street corner Wednesday afternoon after he pointed what the officers believed was a gun at them, authorities said. The object, however, turned out to be a metal pipe with a knob on it.

The shooting drew a tense, charged crowd of dozens to the streets of Crown Heights. The Police Department had encountered the man before and classified him as emotionally disturbed.

Five officers were responding to three 911 calls about a man threatening people with a silver gun near the corner of Montgomery Street and Utica Avenue in Crown Heights, Terence A. Monahan, the chief of the department, said at a news conference.

“The suspect then took a two-handed shooting stance and pointed an object at the approaching officers,’’ Monahan said.

Monahan said four of the officers fired 10 bullets in all. The man, identified by his father as Saheed Vassell, 34, was pronounced dead after being taken to Kings County Medical Center.

NEW YORK TIMES