In a perfect world, all the students who came out of the building would have been directed to an enclosed/cordoned-off area, to be contained until they could be sorted through and individually questioned. I’ve tried to find out if Cruz had dumped his weapons before leaving the school, but couldn’t find any clarification on that issue.
He did dump them along with his vest and bookbag and duffle bag
Video showed him running through the school parking lot.
This is a very good summary.