Police officers in New York City fatally shot an unarmed black man who was pointing what appeared to be a gun at them on Wednesday, police said.

The object turned out to be a metal pipe with a knob on the end. The man reportedly suffered from mental illness including bipolar disorder.

Officers responded to three 911 calls at around 4:40 p.m. describing a man wielding “a silver firearm,” who was “pointing it at people on the street,” on a corner in the Crown Heights neighborhood in Brooklyn, the NYPD Chief of Department Terence Monahan told reporters.

Four of the five police officers who responded to the scene fired on the man after he took a “two-handed shooting stance and pointed an object at the approaching officers,” Monahan said.

Three of the four officers who fired at Vassell were not in uniform, Monahan said. He told reporters they fired a total of 10 rounds at Vassell. None of them were wearing body cameras.

The man, identified by The New York Times as 34-year-old Saheed Vassell, was pronounced dead at Kings County Hospital.

Vassell’s father Eric Vassell told the Times his son had bipolar disorder and had been hospitalized multiple times in recent years. Residents told news outlets that the younger Vassell was well-known in the neighborhood as “mentally ill but generally harmless.”

Members of the crowd “wept” at how the shooting fell on the 50th anniversary of Martin Luther King Jr.’s assassination. The police shooting of Stephon Clark, another unarmed black man, ignited protests in Sacramento that have lasted weeks.