Law enforcement no longer intervenes to stop killers.
Law enforcement sets up a perimeter and waits until the shooter has killed themselves, then counts up the bodies.
If you are trapped with a mass killer, you will get no help from law enforcement.
Not sure I agree with that entirely, but your point does have merit, as evidenced by this case.
Cops don't extend themselves at all -- its all about keeping themselves safe. Which is understandable to a certain degree, but when it totally supersedes their mandate to "protect and serve," then something needs to change.