Image copyright Reuters Image caption Sgt Hugh Barry had been an officer for eight years

A US police officer has been stripped of his gun and badge after he shot a mentally ill black pensioner dead.

Sgt Hugh Barry was among officers called to Deborah Danner's New York apartment on Tuesday evening to reports of an "emotionally disturbed person".

He persuaded her to drop a pair of scissors, but shot her twice after she tried to hit him with a baseball bat.

The killing has sparked outrage - not just because of the 66-year-old's race, but also her fragile mental state.

New York Mayor Bill de Blasio said on Wednesday she "should be alive right now", while NYPD Commissioner James O'Neil said his department had "failed".

"It's not how we train; our first obligation is to preserve life, not to take a life when it can be avoided," he said.

Blame

New York City police respond to 128,000 calls about emotionally disturbed people each year, and are supposed to use techniques to "de-escalate" a situation, rather than resort to force.

They had already come to Ms Danner's apartment on a number of occasions, each time taking her to hospital.

It is not known why Sgt Barry, who had been an officer for eight years and was equipped with a stun gun, did not follow his training.

But Ed Mullins, the head of the police union representing sergeants, argued the shooting was self defence - and Sgt Barry was being used as a political pawn.

"They're taking the weak political spot and blaming the sergeant for everything," Mullins said. "I'm not surprised. [Mr de Blasio is] up for election next year."

Police shootings have come to the fore in the US in recent years, with the black community suffering disproportionately.

In 2015, US police officers killed 346 black people, according to Mapping Police Violence.

Anger over the shootings started the Black Lives Matter campaign.