Tip:
We always talk about being able to hit our target. We talk about penetration and overpenetration. What many people forget is that we need to limit our liability by NOT MISSING.
Liability:
Errand rounds can harbor severe liability for the shooter if these rounds strike a bystander. Think of the NYPD shooting in 2012. The shooting took place at the base of the Empire State Building where, while the perpetrator was shot, 9 bystanders were also struck. The department was subsequently sued.
Training:
While I do not wish to downplay the need of the officers to use deadly force in this circumstance, however it speaks to the need for training. All bullets should be recoverable, and all shots should be on target or should not be fired.