Not specific to just the on-scene (non)action, but the department policies in general, their collusion with the school board, and their actions re the 39 calls on the killer prior to the killlings.
https://theconservativetreehouse.com/2018/02/23/broward-county-sheriffs-office-did-not-miss-warning-signs-or-make-mistakes/
Broward County Sheriff’s Office Did Not “Miss Warning Signs” or Make “Mistakes”…
Excerpts:
A few points need to be emphasized for those unfamiliar with the Broward County system. First, with revelations of frequent LEO contact and calls from people warning about school shooter Nikolas Cruz, there’s a common narrative mistakenly being pushed by mainstream media.
The Broward County Sheriff’s Office (BSO) didn’t “miss warning signs” or make “mistakes” in not writing up reports. The Sheriff’s office did exactly what their internal policies, procedures and official training required them to do, they intentionally ignored the signs, and intentionally didn’t generate documents. Example:
Miami Herald […] In November, a tipster called BSO to say Cruz “could be a school shooter in the making” but deputies did not write up a report on that warning. It came just weeks after a relative called urging BSO to seize his weapons. Two years ago, according to a newly released timeline of interactions with Cruz’s family, a deputy investigated a report that Cruz “planned to shoot up the school” — intelligence that was forwarded to the school’s resource officer, with no apparent result.

I often wonder what could have been done based on the warning signs.
People say this guy was weird, and they thought he would be the type to shoot up the place.
He had a large number of police calls to his residence for behavioral issues
He apparently made some level of threats towards this type of incident.
Is this enough to put him on a no-buy list?
Is it enough to lock him away in a mental health facility for a period of time?
Is it enough to block his civil rights in any way?
Specifically, what is the course of actions? Should the school or police have asked the court to consider a mandatory mental health evaluation? Should he be entered into some NCIC database so he would show up when doing a background check?
If the cops did the very least and went to the boys house to talk to him and he denied planning any sort of event, then what do they do?
When looking at these incidents I hear so many accounts of "warning signs" but I have a hard time finding whether any of them would have justified taking away his civil rights.
Examples:
He was very quiet
He was weird
He didn't like others
People didn't like him.
Heck, I could have been one of those guys people at school would have said would be the one most likely to shoot up a school.