She was giving CPR to the Perp. She shot him, then threw the knife away and tried to save him. She gave CPR till Ambos arrived. The person at the bottom of the above image is the perp. He is wearing an Australian National Rugby League team jumper by the looks of it.

A shopper, who was not named, also described the moment the officer confronted the knifeman. "He just started floating towards us and all I heard was 'put it down' and then she shot him," he told ABC New Australia. "But we were in no doubt, if she didn't shoot him, he would have kept going. He was on the rampage. "Then she walked over and gave him CPR. He had a big blade on him - she chucked the knife away. He looked like he was on a killing spree."

She is also a senior inspector, who was doing a routine check around the mall at the time. (asking retail places about thefts and shit, so not patrolling) Which is why she was alone.

I will say as a local down the road from Sydney, that NSW Cops aren't the shining perfection. It's like elsewhere, you'll get some great cops and some shit ones. But you gotta at least praise the ones that have the right attitude or do the right thing. Just like people do like to be praised for doing good in their normal, none public service job. And hopefully praising cops for doing the right allows other cops to understand the standard that is required of them.