Those cops were on point. They didn't instantly shoot, they bagged first, the only failure I see is their weapon handling (or lack thereof).
Poor woman, hopefully wherever she is now she can move freely.
I wouldn't say it was their weapon handling that got her shot, but their inability to use tactics other than shouting and shooting. The officer who's perspective we're seeing was the only one with a remotely clear shot at the guy yet they all decided multiple shots were an appropriate response. The outcome can't have been a surprise to any of them.
Lethal force is entirely justified when dealing with someone armed with a knife, but as EVH said they forced that situation to rapidly escalate and clearly had no plan for how to deal with it once they pushed him back.