Clare Nowland, a “much-loved lady”, was in a critical condition following the confrontation at her nursing home on Wednesday, New South Wales state police assistant commissioner Peter Cotter said.

“We are very concerned about what occurred the other day. And that’s why we have the investigation,” Cotter told media in Sydney, alluding to a previously announced probe.

“At the time she was tasered, she was approaching police but it’s fair to say at a slow pace. She had a walking frame but she had a knife.”

Officers were sent to Yallambee Lodge in southern New South Wales after being alerted that a woman was “armed with a knife”, police said in a statement.

Paramedics and police had urged Nowland to drop the serrated steak knife in a conversation lasting “a number of minutes” before she moved towards them, prompting one officer to fire his taser at her, Cotter said.

She then fell backwards and struck her head on the ground, according to police.

“The officer’s duty status is under review,” police said.

It took days for police to confirm they had tasered the aged-care resident, whom local media described as a great-grandmother with dementia.

Ambulance paramedics treated the woman and took her to Cooma District Hospital, police said.

Police body cameras had captured “confronting” footage of the incident, which would form a central part of the investigation, Cotter said.

The footage is not being released for the time being, he added.

On the day of the tasering, police said only that Nowland had “sustained injuries during an interaction with police”.

A team including homicide squad officers had opened a “critical incident investigation”, including “the discharge of a taser” police said.

The probe is subject to independent review.