Pepper spray has an effective range of 10 feet, not enough distance for the Tueller Drill. Tasers have an effective range of 15 feet.
edit. Woops, the Tueller Drill is holstered and not drawn, but still gives some us data on this.
https://en.wikipedia.org/wiki/Tueller_Drill
We trained the Tueller Drill three times a year, and once more during fire arm qualification. Even in a training situation, with a fake knife, the danger response is unreal.
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Addressing some other things mentioned in the replies:
Tazer - see above. 15ft range, which is best case range. That isn't real life at all. When using a tazer on a moving target, the effective range is unfortunately not reliable at all. You also have to account for what this person is wearing. Taking chances with a non-lethal weapon (tazer) versus an approaching subject with a lethal weapon, is a gamble to say the least.
The same goes with pepper spray, aka capstun. Actually using it in this situation, might or might not work well at all. It doesn't STOP anyone from continuing their goal. It might slow them down because of vision issues, but they can still violently slash around with a knife. It can also affect the officer using the spray, causing even more dangerous situation. Go out and spray this stuff in an attack, outside.. yeah. It doesn't work well.
Non-lethal bullets.. that would be ideal, to keep from having to take a life. Couple issues with that. You need to carry it with it you at all times for situations like this. If you have it in your car, and have time to get it, then safely use it, I'm all for it. Did these officers have that option? If delaying the attack by backing up, talking to the subject, gives another officer time to get to their car, grab the beanbag shotgun, and use it, I'm 100% for that. Armchair guessing in this case is just that, guessing.
Shooting at limbs to immobilize a subject is probably one of the most DO NOT do things in real life. It's just ludicrous. Stop watching movies.
Comparing this particular situation to any other situation from any other company isn't accurate at all. There's no real idea on how this exact situation with this exact person would have happened/ended in any other city, state, country, etc. Doing that has sooo much assumption/speculation/guessing, etc.