Knife-Wielding Georgia Tech Student Killed by Police on Campus

Play stupid games; win stupid prizes.

Is there any other way than killing the man wielding knife? Can't the police shoot him in the leg or arm just to incapacitate him?

This is absolute stupidity.
This is not a video game, this is not television.
The gun is a DEADLY weapon. If you were ever in this situation, you are so charged with adrenaline, you can barely feel your arms, much less aim carefully.
Police are trained that if a situation is dangerous enough to draw a gun, you MUST SHOOT TO KILL. Center mass. (In fact, in cases where the target had a gun, something less than 1/4 of cops shots land on the target at all.)

Criminals need to understand that when a gun is out, the seriousness is now at 11. They MUST comply, or they might get killed.

To suggest that officers should or would shoot to 'injure' would only mean cops are risking their lives even more, and that criminals would have an incentive not to take a gun seriously.