NEW YORK — Mayor Bill de Blasio, speaking in strikingly blunt terms, said Wednesday that the fatal police shooting of a mentally ill 66-year-old woman in the Bronx was "tragic and unacceptable."

The woman, Deborah Danner, had a long history of mental illness, and de Blasio said the sergeant who fired the fatal shot had failed to follow police department protocol for dealing with the woman.

"It should never have happened. It's as simple as that," the mayor said at a midday news conference at City Hall, echoing the comments made by Police Commissioner James P. O'Neill earlier Wednesday.

The sergeant, Hugh Barry, an eight-year veteran of the department, was stripped of his gun and badge and placed on modified duty within hours of the shooting, which happened early Tuesday evening in the Castle Hill neighborhood.

The action against the sergeant and the condemnation of his conduct were notable for how quickly and unequivocally the commissioner and the mayor responded to the shooting, which, like all police-involved shootings, will be the subject of lengthy investigations by the department and by prosecutors.

"What is clear in this one instance: We failed," O'Neill said at a news briefing Wednesday. "I want to know why it happened."

The building in the Castle Hill neighborhood of the Bronx where Deborah Danner was fatally shot by the police. (Gregg Vigliotti/The New York Times)
The building in the Castle Hill neighborhood of the Bronx where Deborah Danner was fatally shot by the police. (Gregg Vigliotti/The New York Times)

The episode was unfolding at a crucial moment, amid a heated national debate about race and the use of force by the police, and just one month into O'Neill's tenure as commissioner.

De Blasio said that the sergeant had failed to take steps that could have avoided the fatal confrontation, including waiting for the arrival of the specialized Emergency Services Unit, using his Taser or requesting that police negotiators be sent to the scene. "There was an opportunity to slow things down here and wait to get everything set up the right way," he said.

The New York Police Department has expanded the availability of Tasers in the last year in an attempt to reduce the use of firearms, training an additional 4,000 officers to use the devices and nearly tripling the number in circulation.

Several elected officials, including the Bronx borough president, Ruben Diaz Jr., and the City Council speaker, Melissa Mark-Viverito, as well as Deborah Danner's sister, Jennifer Danner, called for an investigation by the state attorney general.

Amy Spitalnick, a spokeswoman for the New York attorney general, Eric T. Schneiderman, said that the office would review the shooting to see if it fell under the attorney general's jurisdiction to investigate the deaths of civilians killed by law enforcement officers, a power created by an executive order by Gov. Andrew M. Cuomo in 2015.

"We extend our deepest condolences to Ms. Danner's family," Spitalnick said.

On Tuesday, police arrived at the building around 6 p.m. after receiving a 911 call about an emotionally disturbed person. Neighbors said Danner had been acting erratically around that time.

Barry, who was in uniform, entered Danner's seventh-floor apartment and found her in a bedroom holding a pair of scissors, the police said. At some point during their exchange, she put down the scissors, picked up a baseball bat and tried to hit him with it, police said. The sergeant fired two shots, striking Danner in her torso.

The whole exchange lasted about 15 to 20 minutes, and the shooting occurred in close quarters, police said. Danner died at Jacobi Medical Center.

Wallace Cooke Jr., who said he was a cousin of Danner's mother, said Danner learned she had mental illness when she was in college.

"I resent her being dead this morning," said Cooke, a former police officer who retired in 1984 after working for 15 years at the 26th Precinct in Harlem. "It's totally unnecessary to kill a mentally ill person."

For many, the shooting was an echo of the fatal police shooting in 1984 of another 66-year-old woman, Eleanor Bumpurs, who was shot twice with a shotgun as officers were trying to help marshals evict her from a public housing apartment. The officer who shot her, Stephen Sullivan, said that Bumpurs was armed with a kitchen knife, and Sullivan was later acquitted of a manslaughter charge.

Diaz said in an interview that he appreciated the commissioner's tone of remorse but that the circumstances of Danner's killing called out for review.

"Was it absolutely necessary to shoot Ms. Danner once, let alone twice?" he said. "A 66-year-old elderly woman with a medical condition is dead today. We all have to do better."

De Blasio said police had been called to the building because of Danner's behavior several other times.

She had not worked for years and lived alone, Cooke said.