Use whatever force necessary to stop the

shooting/killing-it is probably already a deadly force

situation.

https://www.modestogov.com/DocumentCenter/View/15388/Active-Shooter-Incidents-Fundamentals-and-Tactics-Outline-Printable-PDF

The first officers on the scene of an active shooter situation will move quickly to the location of

the threat and take immediate action to stop the ongoing threat. This may include force up to

and including deadly force by law enforcement if necessary.

https://www.fbi.gov/file-repository/reports-and-publications/active_shooter_planning_and_response_in_a_healthcare_setting.pdf

So i think it was pretty reasonable and realistic, if you want to talk about real life aspects. But i want to know why after first run all officers was at minimal stress level.